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Background: Sweat chloride (SC) concentrations in people with cystic fibrosis (PwCF) reflect relative CF transmembrane conductance regulator (CFTR) protein function, the primary CF defect. Populations with greater SC concentrations tend to have lesser CFTR function and more severe disease courses. CFTR modulator treatment can improve CFTR function within specific CF genotypes and is commonly associated with reduced SC concentration. However, SC concentrations do not necessarily fall to concentrations seen in the unaffected population, suggesting potential for better CFTR treatment outcomes. We characterized post-modulator SC concentration variability among CHEC-SC study participants by genotype and modulator., Methods: PwCF receiving commercially approved modulators for ≥90 days were enrolled for a single SC measurement. Clinical data were obtained from chart review and the CF Foundation Patient Registry (CFFPR). Variability of post-modulator SC concentrations was assessed by cumulative SC concentration frequencies., Results: Post-modulator SC concentrations (n = 3787) were collected from 3131 PwCF; most (n = 1769, 47 %) were collected after elexacaftor/tezacaftor/ivacaftor (ETI) treatment. Modulator use was associated with lower SC distributions, with post-ETI concentrations the lowest on average. Most post-ETI SC concentrations were <60 mmol/L (79 %); 26 % were <30 mmol/L. Post-ETI distributions varied by genotype. All genotypes containing at least one F508del allele had individuals with post-ETI SC ≥60 mmol/L, with the largest proportion being F508del/minimal function (31 %)., Conclusions: Post-modulator SC concentration heterogeneity was observed among all genotypes and modulators, including ETI. The presence of PwCF with post-modulator SC concentrations within the CF diagnostic range suggests room for additional treatment-associated CFTR restoration in this population., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Rationale: Pulmonary exacerbations (PEx) remain the most common cause of morbidity, recurrent hospitalization, and diminished survival in people with cystic fibrosis (PWCF) and are characterized by excess inflammation. Corticosteroids are potent, widely available antiinflammatory drugs. However, corticosteroid efficacy data from randomized controlled trials in PWCF are limited. Objectives: To determine whether adjunctive systemic corticosteroid therapy is associated with improved outcomes in acute CF PEx. Methods: We performed a secondary analysis of Standardized Treatment of Pulmonary Exacerbations 2 (STOP2), a large multicenter randomized controlled trial of antimicrobial treatment durations for adult PWCF presenting with PEx, that included the use of corticosteroids as a stratification criterion in its randomization protocol. Corticosteroid treatment effects were determined after propensity score matching for covariates including age, sex, baseline forced expiratory volume in 1 second (FEV 1 ), genotype, and randomization arm. The primary outcome measure was the change in percentage predicted FEV 1 (ppFEV 1 ). Symptoms, time to next PEx, and the incidence of adverse events (AEs) and serious adverse events (SAEs) were assessed as secondary endpoints. Phenotypic factors associated with the clinical decision to prescribe steroids were also investigated. Results: Corticosteroids were prescribed for 168 of 982 PEx events in STOP2 (17%). Steroid prescription was associated with decreased baseline ppFEV 1 , increased age, and female sex. Cotreatment with corticosteroids was independent of treatment arm allocation and did not result in greater mean ppFEV 1 response, longer median time to next PEx, or more substantial symptomatic improvement compared with propensity-matched PWCF receiving antibiotics alone. AEs were not increased in corticosteroid-treated PWCF. The total number of SAEs-but not the number of corticosteroid-related or PEx-related SAEs-was higher among patients receiving corticosteroids. Conclusions: Empiric, physician-directed treatment with systemic corticosteroids, although common, is not associated with improved clinical outcomes in PWCF receiving antibiotics for PEx. Clinical trial registered with www.clinicaltrials.gov (NCT02781610).

Rationale: Rates of viral respiratory infection (VRI) are similar in people with cystic fibrosis (CF) and the general population; however, the associations between VRI and CF pulmonary exacerbations (PEx) require further elucidation. Objectives: To determine VRI prevalence during CF PEx and evaluate associations between VRI, clinical presentation, and treatment response. Methods: The STOP2 (Standardized Treatment of Pulmonary Exacerbations II) study was a multicenter randomized trial to evaluate different durations of intravenous antibiotic therapy for PEx. In this ancillary study, participant sputum samples from up to three study visits were tested for respiratory viruses using multiplex polymerase chain reactions. Baselines and treatment-associated changes in mean lung function (percent predicted forced expiratory volume in 1 s) , respiratory symptoms (Chronic Respiratory Infection Symptom Score), weight, and C-reactive protein were compared as a function of virus detection. Odds of PEx retreatment within 30 days and future PEx hazard were modeled by logistic and Cox proportional hazards regression, respectively. Results: A total of 1,254 sputum samples from 621 study participants were analyzed. One or more respiratory viruses were detected in sputum samples from 245 participants (39.5%). Virus-positive participants were more likely to be receiving CF transmembrane conductance regulator modulator therapy (45% vs. 34%) and/or chronic azithromycin therapy (54% vs. 44%) and more likely to have received treatment for nontuberculous Mycobacterium infection in the preceding 2 years (7% vs. 3%). At study visit 1, virus-positive participants were more symptomatic (mean Chronic Respiratory Infection Symptom Score, 53.8 vs. 51.1), had evidence of greater systemic inflammation (log 10 C-reactive protein concentration, 1.32 log 10 mg/L vs. 1.23 log 10 mg/L), and had a greater drop in percent predicted forced expiratory volume in 1 second from the prior 6-month baseline (5.8 vs. 3.6). Virus positivity was associated with reduced risk of future PEx (hazard ratio, 0.82; 95% confidence interval, 0.69-0.99; P  = 0.034) and longer median time to next PEx (255 d vs. 172 d; P  = 0.021) compared with virus negativity. Conclusions: More than one-third of STOP2 participants treated for a PEx had a positive test result for a respiratory virus with more symptomatic initial presentation compared with virus-negative participants, but favorable long-term outcomes. More refined phenotyping of PEx, taking VRIs into account, may aid in optimizing personalized management of PEx.Clinical trial registered with www.clinicaltrials.gov (NCT02781610).

Antibiotics are frequently utilized for cystic fibrosis (CF)-related pulmonary exacerbation treatment. The antibiotic spectrum index (ASI) is an antimicrobial stewardship tool developed to compare the relative breadth of individual antibiotics. This study aimed to create two expanded CF-specific ASI scoring indices for use in antimicrobial stewardship research and clinical care. The first scoring index expanded the original ASI to include bacterial microorganisms common to CF airway infections (CF-ASI). The second scoring system only included scores for bacterial microorganisms classically identified in CF airway infections (CF-sASI). Sixty-two antibiotics were evaluated and included in the updated ASIs. When multiple antibiotics are prescribed, we proposed using an additive ASI approach whereby the sum of the individual prescribed antibiotic scores represents the total ASI score. The application of CF-focused ASIs into CF research and stewardship programs can help to optimize antibiotic benefits, minimize harms and allow for increased sustainability of antibiotic use in CF., Competing Interests: Declaration of competing interest Dr. VanDevanter notes consulting fees from Arcturus, Arrevus, BiomX, Clarametryx, Enbiotix, Microbion, Pyros, Respirion, and Zambon. Drs. Cogen, Heltshe, Brothers, Gerber, Kronman and Somayaji have no reflect conflict of interests to disclose., (Copyright © 2024. Published by Elsevier B.V.)

Background: Opportunistic bacterial infection is a hallmark of cystic fibrosis (CF) lung disease and early mortality. Poorly characterized prevalence changes have accompanied two decades of health improvements, with CFTR modulators likely to further affect infection epidemiology., Methods: Bacterial prevalence change trends across birth cohorts were assessed with linear regression using 2001-2019 US CF Foundation Patient Registry data. Informative missingness was assessed, as was age-to-age infection status., Results: Bacterial prevalence constantly changed from 2001 to 2019, with changes differing across birth cohorts. Informative censoring affected prevalence change for some organisms. Age-to-age infection status changes were greater than net changes in bacterial prevalence and varied by age., Conclusions: CF infection epidemiology changed over two decades and will continue to do so. Understanding how modulators affect infection epidemiology will require creative designs for longitudinal prevalence change studies emphasizing prevalence changes independent of effects on lung biology., Competing Interests: Declaration of Competing Interest The authors have no competing interests relative to this content to report. MWK received salary support to his institution from the Cystic Fibrosis Foundation and the National Institutes of Health (UL1TR002548). JJL received salary support from the Cystic Fibrosis Foundation (CAVERL22AB0)., (Copyright © 2023 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

CF registry pulmonary exacerbation (PEx) analyses have employed "before and after" spirometry recovery, where the best percent predicted forced expiratory volume in 1 s (ppFEV 1 ) prior to PEx ("baseline") is compared to the best ppFEV 1 <3 months post-PEx. This methodology lacks comparators and ascribes recovery failure to PEx. Herein, we describe 2014 CF Foundation Patient Registry PEx analyses including a comparator: recovery around nonPEx events, birthdays. 49.6% of 7357 individuals with PEx achieved baseline ppFEV 1 recovery while 36.6% of 14,141 achieved baseline recovery after birthdays; individuals with both PEx and birthdays were more likely to recover baseline after PEx than after birthdays (47% versus 34%); mean ppFEV 1 declines were 0.3 (SD=9.3) and 3.1 (9.3), respectively. Post-event measure number had more effect on baseline recovery than did real ppFEV 1 loss in simulations, suggesting that PEx recovery analyses lacking comparators are prone to artifact and poorly describe PEx contributions to disease progression., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

Background: Pulmonary exacerbations (PEx) remain a major cause of morbidity and mortality in people with cystic fibrosis (PWCF). Although the combination cystic fibrosis transmembrane conductance regulator (CFTR) modulators lumacaftor/ivacaftor and tezacaftor/ivacaftor have been shown to reduce PEx frequency, their influence on clinical and biochemical responses to acute PEx treatment is unknown., Methods: We performed a secondary analysis of STOP2, a large multicenter randomized controlled trial of antimicrobial treatment durations for adult PWCF presenting with PEx. Propensity score matching was used to compare outcomes in antibiotic-treated F508del/F508del PWCF receiving lumacaftor/ivacaftor or tezacaftor/ivacaftor with those observed in antibiotic-treated F508del/F508del controls not receiving CFTR modulator therapy. The primary outcome measure was the change in percent predicted FEV 1 (ppFEV 1 ) following completion of intravenous (IV) antibiotics, with post-antibiotic changes in symptoms, serum C-reactive protein (CRP) concentrations and weight included as secondary endpoints., Results: Among 982 PEx events in randomized PWCF, 480 were homozygous for F508del, of whom 289 were receiving lumacaftor/ivacaftor or tezacaftor/ivacaftor at initiation of antibiotic therapy. Modulator-treated F508del/F508del PWCF did not demonstrate greater improvements in ppFEV 1 , symptoms, serum CRP or weight following antibiotic treatment compared to modulator-naïve controls matched for age, sex, baseline ppFEV 1 , genotype, body mass index, initial CRP, initial symptoms, exacerbation history, diabetic status, randomization arm and concomitant medical therapy., Conclusion: In the acute setting, CFTR modulator therapy with lumacaftor/ivacaftor or tezacaftor/ivacaftor does not convey additional clinical or biochemical advantage above standardized PEx treatment in F508del/F508del PWCF., Competing Interests: Declaration of Competing Interest O.J.McE. has been an investigator for Chiesi and Grifols. P.A.F. has been an investigator for Novartis, Novoteris, Proteostasis, Savara, Sound, Chiesi and Vertex. C.H.G. has been an investigator for Boehringer Ingelheim and a DSMB chair for Novartis. The remaining authors have no relevant or competing interests to disclose., (Copyright © 2023. Published by Elsevier B.V.)

Objective: To assess the feasibility of enrolling people with CF (pwCF) taking the CFTR modulator elexacaftor/tezacaftor/ivacaftor (ETI) in clinical trials of a new modulator., Methods: PwCF receiving ETI at CHEC-SC study (NCT03350828) enrollment were surveyed for interest in 2-week to 6-month placebo- (PC) and active-comparator (AC) modulator studies. Those taking inhaled antimicrobials (inhABX) were surveyed for interest in PC inhABX studies., Results: Of 1791 respondents, 75% [95% CI 73, 77] would enroll in a 2-week PC modulator study versus 51% [49, 54] for a 6-month study; 82% [81, 84] and 63% [61, 65] would enroll in 2-week and 6 month AC studies; 77% [74, 80] of 551 taking inhABX would enroll in a 2-week PC inhABX study versus 59% [55, 63] for a 6-month study. Previous clinical trial experience increased willingness., Conclusions: Study designs will affect feasibility of future clinical trials of new modulators and inhABX in people receiving ETI., Competing Interests: Declaration of Competing Interest The authors have no competing or conflicting interests to report., (Copyright © 2023. Published by Elsevier B.V.)

Cystic fibrosis (CF) pulmonary exacerbations (PEx) are clinical events that commonly result in increased treatment burden, decreased quality of life, and accelerated lung disease progression. CF PEx have historically been approached as though dealing with acute infections, and antibiotic treatments have been associated with improved outcomes. In this review, we discuss data supporting a causal role of CF airway infection in PEx as well studies that highlight our knowledge gaps in regard to PEx definitions, pathophysiology, and optimal treatment approaches. In the era of highly effective cystic fibrosis transmembrane conductance regulator modulator therapy, and the continually increasing health and longevity of persons with CF, a better understanding of PEx and further optimization of PEx antibiotic treatment approaches are needed., (© The Author(s) 2022. Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Cystic fibrosis (CF) pulmonary exacerbation (PEx) treatment guidelines suggest that Pseudomonas aeruginosa (Pa) airway infection be treated with two antipseudomonal agents., Methods: We retrospectively studied treatment responses for STOP2 PEx treatment trial (NCT02781610) participants with a history of Pa infection. Mean lung function and symptom changes from intravenous (IV) antimicrobial treatment start to Visit 2 (7 to 10 days later) were compared between those receiving one, two, and three+ antipseudomonal classes before Visit 2 by ANCOVA. Odds of PEx retreatment with IV antimicrobials within 30 days and future IV-treated PEx hazard were modeled by logistic and Cox proportional hazards regression, respectively. Sensitivity analyses limited to the most common one-, two-, and three-class regimens, to only IV/oral antipseudomonal treatments, and with more stringent Pa infection definitions were conducted., Results: Among 751 participants, 50 (6.7%) were treated with one antipseudomonal class before Visit 2, while 552 (73.5%) and 149 (19.8%) were treated with two and with three+ classes, respectively. Females and participants with a negative Pa culture in the prior month were more likely to be treated with a single class. The most common single, double, and triple class regimens were beta-lactam (BL; n = 42), BL/aminoglycoside (AG; n = 459), and BL/AG/fluoroquinolone (FQ; n = 73). No lung function or symptom response, odds of retreatment, or future PEx hazard differences were observed by number of antipseudomonal classes administered in primary or sensitivity analyses., Conclusions: We were unable to identify additional benefit when multiple antipseudomonal classes are used to treat PEx in people with CF and Pa., (Copyright © 2022. Published by Elsevier B.V.)

Chronic polymicrobial airway infections are a hallmark of cystic fibrosis (CF) lung disease. Antibiotic therapy is a primary treatment of CF pulmonary exacerbations (PEx); however, the impact of episodic antibiotic treatment on airway bacterial communities has not been well described. We analyzed sputum samples from adults with CF obtained immediately before and during antibiotic treatment of PEx. Sequencing of the V4 region of the bacterial 16S ribosomal RNA gene was used to assess changes in bacterial community structure during antibiotic treatment. The peak impact of antibiotic treatment was observed by day four or five of treatment. These findings advance our understanding of bacterial community dynamics during antibiotic treatment of PEx and complement recent and ongoing studies evaluating the optimal duration of antibiotic therapy for PEx., (Copyright © 2022. Published by Elsevier B.V.)

Background: In the STOP2 (Standardized Treatment of Pulmonary Exacerbations-2) study, intravenous (IV) antimicrobial treatment duration for adults with cystic fibrosis (CF) experiencing pulmonary exacerbations (PEx) was determined based on initial treatment response. The impact of home vs hospital care remains an important clinical question in CF. Our hypothesis was that STOP2 participants treated at home would have less improvement in lung function compared to those treated in the hospital., Methods: Treating clinicians determined PEx treatment location, which was a stratification factor for STOP2 randomization. Lung function, weight, and symptom recovery were evaluated by treatment location. Propensity scores and inverse probability treatment weighting were used to test for differences in clinical response by treatment location., Results: In all, 33% of STOP2 participants received IV antimicrobials in the hospital only, 46% both in the hospital and at home, and 21% at home only. Mean (95% CI) ppFEV 1 improvement was significantly (p < 0.05) lower for those treated at home only, 5.0 (3.5, 6.5), compared with at home and in the hospital, 7.0 (5.9, 8.1), and in the hospital only, 8.0 (6.7, 9.4). Mean weight (p < 0.001) and symptom (p < 0.05) changes were significantly smaller for those treated at home only compared to those treated in the hospital only., Conclusions: Compared to PEx treatment at home only, treatment in the hospital was associated with greater mean lung function, respiratory symptom, and weight improvements. The limitations of home IV therapy should be addressed in order to optimize outcomes for adults with CF treated at home., (Copyright © 2021. Published by Elsevier B.V.)

Background: The purpose of these analyses was to determine whether overall costs were reduced in cystic fibrosis (CF) patients experiencing pulmonary exacerbation (PEx) who received shorter versus longer durations of treatment., Methods: Among people with CF experiencing PEx, we calculated 30-day inpatient, outpatient, emergency room, and medication costs and summed these to derive total costs in 2020 USD. Using the Kaplan-Meier sample average (KMSA) method, we calculated adjusted costs and differences in costs within two pairs of randomized groups: early robust responders (ERR) randomized to receive treatment for 10 days (ERR-10 days) or 14 days (ERR-14 days), and non-early robust responders (NERR) randomized to receive treatment for 14 days (NERR-14 days) or 21 days (NERR-21 days)., Results: Patients in the shorter treatment duration groups had shorter lengths of stay per hospitalization (mean ± standard deviation (SD) for ERR-10 days: 7.9 ± 3.0 days per hospitalization compared to 10.1 ± 4.2 days in ERR-14 days; for NERR-14 days: 8.7 ± 4.9 days per hospitalization compared to 9.6 ± 6.5 days in NERR-21 days). We found statistically significantly lower adjusted mean costs (95% confidence interval) among those who were randomized to receive shorter treatment durations (ERR-10 days: $60,800 ($59,150 - $62,430) vs $74,420 ($72,610 - $76,450) in ERR-14 days; NERR-14 days: $66,690 ($65,960-$67,400) versus $74,830 ($73,980-$75,650) in NERR-21 days)., Conclusions: Tied with earlier evidence that shorter treatment duration was not associated with worse clinical outcomes, our analyses indicate that treating with shorter antimicrobial durations can reduce costs without diminishing clinical outcomes., Competing Interests: Declaration of Competing Interest Grants from the Cystic Fibrosis Foundation in part supported the salaries of LSG, RNH, DLP, AT, SLH, PAF, CHG, NEW, DBS, DRV, and LK. Grants from the NIH in part supported the salaries of SLH, PAF, and CHG. DBS received payments for committee work from the Cystic Fibrosis foundation. DBS's institution also grant support payments from Gilead Sciences and the CHEST Foundation. DBS received personal payment for participation on an advisory board for Vertex Pharmaceuticals., (Copyright © 2022. Published by Elsevier B.V.)

Background: C-reactive protein (CRP) has been proposed as a biomarker for pulmonary exacerbation (PEx) diagnosis and treatment response. CRP >75mg/L has been associated with increased risk of PEx treatment failure. We have analyzed CRP measures as biomarkers for clinical response during the STOP2 PEx study (NCT02781610)., Methods: CRP measures were collected at antimicrobial treatment start (V1), seven to 10 days later (V2), and two weeks after treatment end (V3). V1 log 10 CRP concentrations and log 10 CRP change from V1 to V3 correlations with clinical responses (changes in lung function and symptom score) were assessed by least squares regression. Odds of intravenous (IV) antimicrobial retreatment within 30 days and future PEx hazard associated with V1 and V3 CRP concentrations and V1 CRP >75 mg/L were studied by adjusted logistic regression and proportional hazards modeling, respectively., Results: In all, 951 of 982 STOP2 subjects (92.7%) had CRP measures at V1. V1 log 10 CRP varied significantly by V1 lung function subgroup, symptom score quartile, and sex, but not by age subgroup. V1 log 10 CRP correlated moderately with log 10 CRP change at V3 (r 2 =0.255) but less so with lung function (r 2 =0.016) or symptom (r 2 =0.031) changes at V3. Higher V1 CRP was associated with greater response. CRP changes from V1 to V3 only weakly correlated with lung function (r 2 =0.061) and symptom (r 2 =0.066) changes. However, V3 log 10 CRP was associated with increased odds of retreatment (P = .0081) and future PEx hazard (P = .0114)., Discussion: Despite consistent trends, log 10 CRP change was highly variable with only limited utility as a biomarker of PEx treatment response., Competing Interests: Declaration of Competing Interest The authors claim no financial conflicts of interest related to this work., (Copyright © 2021 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Rationale: People with cystic fibrosis (CF) experience acute worsening of respiratory symptoms and lung function known as pulmonary exacerbations. Treatment with intravenous antimicrobials is common; however, there is scant evidence to support a standard treatment duration. Objectives: To test differing durations of intravenous antimicrobials for CF exacerbations. Methods: STOP2 (Standardized Treatment of Pulmonary Exacerbations 2) was a multicenter, randomized, controlled clinical trial in exacerbations among adults with CF. After 7-10 days of treatment, participants exhibiting predefined lung function and symptom improvements were randomized to 10 or 14 days' total antimicrobial duration; all others were randomized to 14 or 21 days' duration. Measurements and Main Results: The primary outcome was percent predicted FEV 1 (ppFEV 1 ) change from treatment initiation to 2 weeks after cessation. Among early responders, noninferiority of 10 days to 14 days was tested; superiority of 21 days compared with 14 days was compared for the others. Symptoms, weight, and adverse events were secondary. Among 982 randomized people, 277 met improvement criteria and were randomized to 10 or 14 days of treatment; the remaining 705 received 21 or 14 days of treatment. Mean ppFEV 1 change was 12.8 and 13.4 for 10 and 14 days, respectively, a ‒0.65 difference (95% CI [‒3.3 to 2.0]), excluding the predefined noninferiority margin. The 21- and 14-day arms experienced 3.3 and 3.4 mean ppFEV 1 changes, a difference of ‒0.10 (‒1.3 to 1.1). Secondary endpoints and sensitivity analyses were supportive. Conclusions: Among adults with CF with early treatment improvement during exacerbation, ppFEV 1 after 10 days of intravenous antimicrobials is not inferior to 14 days. For those with less improvement after one week, 21 days is not superior to 14 days. Clinical trial registered with www.clinicaltrials.gov (NCT02781610).

Background: The Characterizing CFTR Modulated Changes in Sweat Chloride and their Association with Clinical Outcomes (CHEC-SC) study is a large epidemiologic study designed to determine the relationship between sweat chloride response and clinical outcomes in people with cystic fibrosis (CF) on commercially approved CFTR modulators. A challenge to study feasibility was capturing sweat chloride measurements before modulator initiation. We tested the hypothesis that historic sweat chloride approximated contemporary pre-modulator values to estimate CFTR modulator-induced changes, allowing a single-visit study design., Methods: GOAL and PROSPECT were multi-center prospective studies of individuals initiating ivacaftor or lumacaftor-ivacaftor. At enrollment, pre-modulator sweat chloride was measured and historic results recorded. Post-modulator sweat chloride was measured at 1, 3 and 6 months. For this analysis, differences between historic and pre-modulator sweat chloride were estimated. CFTR modulator-induced sweat chloride mean changes were compared using historic and pre-modulator sweat chloride., Results: Paired historic and pre-modulator sweat chloride (n=406 participants) revealed a non-significant mean change of -1.0 mmol/L (95% CI: -2.71, 0.66) over an average of 17.2 years. Calculating sweat response to ivacaftor or lumacaftor-ivacaftor using historic or pre-modulator values resulted in similar estimates of modulator response. Based on these results, the CHEC-SC study was designed with a single, post-modulator sweat chloride measurement., Conclusions: Historic sweat chloride values provide a reliable estimate of pre-modulator sweat chloride for people starting on modulator therapy. The CHEC-SC study anticipates capturing approximately 5,000 sweat chloride values, providing an unprecedented understanding of sweat chloride across the CF population in the era of CFTR modulators., Competing Interests: Declaration of Competing Interest ETZ, NMH, DRV, SMR, MWK: grants or consulting CFF; DRV consults for aMoon, Arrevus, Eloxx, Enbiotix, Felix, Ionis, Matinas, Merck, Polyphor, Respirion, Savara; SMR consults for Vertex; MWK consults for Anthera, AzurRx, Celtaxsys, Chiesi, Ionis, Kala, Laurent, Merck, Paranta, pH Pharma, Santhera, Vertex; JPC, KOD and MS: none., (Copyright © 2021. Published by Elsevier B.V.)

The Epidemiologic Study of Cystic Fibrosis (ESCF) was a prospective observational study of over 32,000 people with cystic fibrosis (CF) from 250 clinical care sites in North America from 1994 to 2005. Begun as a pharmacovigilance study in connection with the approval of dornase alfa in 1993, ESCF was open to all people with CF treated at any participating site in the United States or Canada. In addition to obtaining safety and effectiveness data on dornase alfa, ESCF collected encounter-based data to characterize the natural history and management of CF with a special focus on lung disease. During the study, 32,178 patients reported at least one encounter, contributing 869,136 encounters, 622,592 pulmonary function tests, 432,896 cultures, and 118,563 pulmonary exacerbations treated with intravenous antibiotics. Although ESCF data collection concluded in 2005, through a collaboration with the U.S. Cystic Fibrosis Foundation Patient Registry, additional follow-up data through 2017 was available for two-thirds of patients. This allowed for updating of CF genotype and survival information. Fifty-six peer-reviewed publications (cited over 3600 times) resulted from this study. In this manuscript we summarize the published ESCF manuscripts in thematic groups with key study findings and brief comments, and speculate on how ESCF findings will inform future data registries and patient care practices., (© 2021 Wiley Periodicals LLC.)

Background: Chronic lung infections and their treatment pose risks for the development of antimicrobial resistance (AMR) in people with cystic fibrosis (PWCF). In this study, we evaluated the attitudes of healthcare providers' (HCP) and PWCF or their parents' toward AMR within the international CF community., Methods: HCP and PWCF identified through listservs and CF-related organizations were asked to complete an AMR centered survey, with additional questions on antimicrobial stewardship (AMS) for HCP. Descriptive analyses are reported., Results: The responding 443 HCP and 464 PWCF/Parents were from 30 and 25 countries, respectively. Sixty-two percent of HCP and 56% of PWCF stated they were "very concerned" about AMR, with Pseudomonas spp. and Burkholderia spp. considered the most concerning organisms for both HCP and PWCF/Parents. Non-tuberculous mycobacteria were of greater concern to HCP compared to PWCF/Parents. There was a discrepancy regarding AMR education to PWCF, with 80% of HCP stating having discussed this with PWCF/Parents, but only 50% of PWCF recalling such discussions., Conclusion: These results highlight that AMR is relevant to CF HCP and PWCF internationally, indicating that educational tools and research are warranted., (Copyright © 2020. Published by Elsevier B.V.)

Background Antimicrobial susceptibility testing (AST) of bacterial isolates is a time- and resource-intensive procedure recommended by cystic fibrosis (CF) treatment guidelines for antimicrobial selection for pulmonary exacerbation (PEx) treatment. Methods We studied relationships between Pseudomonas aeruginosa (Pa) isolate AST results, antipseudomonal PEx treatments, and treatment responses as change in weight and percent predicted forced expiratory volume in 1 s (ppFEV 1 ) as well as future antimicrobial treatment hazard for PEx occurring at a CF care center from 1999 through 2018. Treatments were categorized by "Pa coverage" as complete (all Pa isolates susceptible by AST to at least one administered agent), none (no isolates susceptible), incomplete (some, but not all isolates susceptible), and indeterminant (administered antipseudomonals not evaluated by AST). Weight and ppFEV 1 responses were compared across Pa coverage categories using unadjusted and adjusted general estimating equations; hazard of future treatment was assessed by Cox and logistic regression. Results Among 3820 antimicrobial PEx treatment events in 413 patients with Pa, 62.6% (2390) had complete Pa coverage; 8.9% (340), 2.4% (99), and 26.2% (1000), had no, incomplete, and indeterminant Pa coverage, respectively. Mean baseline to follow-up weight change was +0.74 kg [95% CI 0.63, 0.86]; ppFEV 1 change was +1.60 [1.29, 1.90]. Pa coverage category was not associated with significant differences in weight or ppFEV 1 change or with future antimicrobial treatment hazard. Conclusions We did not observe superior responses for AST-defined complete Pa coverage treatments versus lesser coverage treatments, suggesting that AST may be of little utility in choosing antimicrobials for CF PEx treatment., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Introduction: Symptom improvement was assessed as changes in the Chronic Respiratory Infection Symptom Score (CRISS) during intravenous antimicrobial exacerbation treatments among subjects from study NCT02109822., Methods: Median daily CRISS reduction (i.e., improvement) and covariates associated with CRISS reduction by Day 14 were assessed by logistic regression., Results: Among 173 subjects, median baseline CRISS was 49 [IQR 41, 56]; 93.6% had a CRISS reduction of ≥11 (minimal clinically important difference); median time to -11 reduction was 2 days [95% CI 2, 3]. The greatest median CRISS difference from baseline, on Day 17, was -26 [-29, -23]. Odds of -26 CRISS change by Day 14 were greater in subjects with higher baseline CRISS (P=.006) and younger ages (P=.041)., Conclusions: CRISS response has good dynamic range and may be a useful efficacy endpoint for PEx interventional trials. The optimal use of CRISS change as an endpoint remains uncharacterized., Competing Interests: Declaration of Competing Interest None, (Copyright © 2020 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Background: Cystic fibrosis (CF) pulmonary exacerbations can be serious respiratory events and reduction in exacerbation rate or risk are important efficacy endpoints for CF therapeutic trials. Variability in exacerbation diagnoses and treatment have led drug developers to employ "objective" exacerbation definitions combining antimicrobial treatment (AT) and the presence of ≥4 of 12 respiratory criteria (first published by Fuchs et al. [NEJM 1994;331(10):637-42]). Assumptions underlying this approach have yet to be formally evaluated., Methods: Respiratory events (RE) observed during a 48-week trial of ataluren (NCT02139306), a read-through agent for premature nonsense codons, were compared across six exacerbation definitions: any AT, intravenous AT (IVAT), ≥4 Fuchs criteria present, AT plus ≥4 Fuchs criteria, IVAT plus ≥4 Fuchs criteria, and investigator assessment. Fuchs definitions were evaluated by assessing missingness of individual criteria and associations between criteria presence and clinician exacerbation assessment., Results: Among 751 RE, more than one third had ≥4 Fuchs criteria present but were not assessed as exacerbations by investigators. Data for ≥1 and for 4 Fuchs criteria, respectively, were missing for ~ 90% and >30% of RE. Only 6/12 Fuchs criteria were present more often when investigators assessed RE as exacerbations than when they did not., Conclusions: "Objective" definitions have shortcomings inconsistent with their purpose of optimizing exacerbation capture in clinical trials : 1) they capture events clinicians do not consider exacerbations, 2) are prone to data missingness which can bias the likelihood of meeting the definition, and 3) employ criteria that are not associated with investigator assessment of exacerbation., Competing Interests: Declaration of Competing Interest DRV reports personal fees from AbbVie, Aradigm, Arrevus, Calithera, Cystic Fibrosis Foundation, Chiesi, Eloxx, Enbiotix, Galephar, Matinas, Armata, Horizon, IBF, Ionis, Kala, Microbion, Recida, Respirion, Vast, and aMoon, outside the submitted work. NMH reports personal fees from Calithera and Kala outside the submitted work. NS has nothing to disclose. JM was an employee of PTC Therapeutics during the conduct of the study. MWK reports grants and personal fees from Anthera, AzurRx, Corbus Pharmaceuticals, Laurent Pharmaceuticals, PTC Therapeutics, Savara, and Vertex Pharmaceuticals, as well as personal fees from Albumedix, Celtaxsys, Chiesi, Genentech, Kala, Novartis, Pharmaceuticals, Merck, Paranta Biosciences, pH Pharma, Protalix Biotherapeutics, and Santhera and grants from the Cystic Fibrosis Foundation and the National Institutes of Health outside the submitted work., (Copyright © 2020. Published by Elsevier B.V.)

Rationale: Considerable morbidity and disease progression in people with cystic fibrosis (CF) result from pulmonary exacerbations (PExs). PEx guidelines note insufficient evidence to recommend for or against the concomitant use of inhaled and intravenous antibiotics. Objectives: We hypothesize that the addition of inhaled antibiotics for PEx therapy is associated with improvements in lung function and a longer time to next PEx compared with standard intravenous antibiotics alone. Methods: We performed a retrospective cohort study using the CF Foundation Patient Registry-Pediatric Health Information System linked dataset. People with CF were included if they were hospitalized for PEx between 2006 and 2016 and 6 to 21 years of age. Lung function outcomes were assessed by linear mixed effect modeling and generalized estimating equations. The time to next PEx was assessed by Cox proportional hazards regression. To estimate independent causal effects while accounting for indication bias and other confounders, inverse probabilities of treatment weights were calculated based on covariates believed to influence the likelihood of inhaled antibiotic use during PEx treatment. Results: A total of 3,253 children and adolescents contributed 9,040 PEx events for analysis. Inhaled antibiotics were used in 23% of PEx events but were not associated with better pre- to post-PEx percent predicted forced expiratory volume in 1 second responses (mean difference, -1.11%; 95% confidence interval [CI], -1.83 to -0.38; P  = 0.003), higher odds of returning to lung function baseline (odds ratio, 0.94; 95% CI, 0.82 to 1.07; P  = 0.34), or longer time to next PEx (hazard ratio, 1.05; 95% CI, 0.99 to 1.12; P  = 0.098). Conclusions: The addition of inhaled antibiotics to standard intravenous antibiotic PEx treatment was not associated with improved lung function outcomes or a longer time to next PEx.

Progress in the development of new therapies for cystic fibrosis (CF) has benefited from therapeutically responsive biomarkers to streamline drug development. Paradoxically, these response biomarkers have been proven to be essential even in the presence of data demonstrating a lack of correlation with clinical outcomes across individuals with CF. This finding is unsurprising, particularly in the setting of a rare disease given complex disease processes and an often-limited pool of clinically effective therapies by which to link biomarkers and clinical responsiveness. While many response biomarkers will be unable to progress from their status as markers of biological efficacy to either established correlates of clinical efficacy or surrogate endpoints, they remain critical to the overall success of therapeutic development., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

As CFTR modulator therapy transforms the landscape of cystic fibrosis (CF) care, its lack of uniform access across the globe combined with the shift towards a new standard of care creates unique challenges for the development of future CF therapies. The advancement of a full and promising CF therapeutics pipeline remains a necessary priority to ensure maximal clinical benefits for all people with CF. It is through collaboration across the global CF community that we can optimize the evaluation and approval process of new therapies. To this end, we must identify areas for which harmonization is lacking and for which efficiencies can be gained to promote ethical, feasible, and credible study designs amidst the changing CF care landscape. This article summarizes the counsel from core advisors across multiple international regions and clinical trial networks, developed during a one-day workshop in October 2019. The goal of the workshop was to identify, in consideration of the highly transitional era of CFTR modulator availability, the drug development areas for which global alignment is currently uncertain, and paths forward that will enable advancement of CF therapeutic development., Competing Interests: Declaration of Competing Interest NMH serves as a consultant through her institution in her role as Executive Director of the CF Therapeutics Development Network Coordinating Center (CF TDNCC) and has received personal consulting fees from Kala Pharmaceuticals and Calithera. She has received grant funding from the Cystic Fibrosis Foundation (CFF) and National Institutes of Health (NIH). SvKR has received personal consulting fees from Antabio, Proteostasis Therapeutics (PTI), and Vertex Pharmaceuticals (VRTX). She has received grant support to her institution for her participation in the European Union HORIZON 2020 work. DPN serves as a consultant through his institution in his role as Medical Director of CF TDNCC. He has received grant support to his Institution from the CFF and Gilead Sciences. DRV has received personal consulting fees from AbbVie, Albumedix, AN2, Aradigm, Armata, Arrevus, Calithera, Chiesi USA, Cipla, Corbus, CFF, Eloxx, Enbiotix, Eveo, Galephar, Horizon, IBF, ICON clinical sciences, Ionis, Kala, Merck, Microbion, NDA, Protalix, PTC, Pulmocide, Recida, Savara, Vast, and VRTX. JCD has received other support from Aligipharma AS, Bayer AG, BI, Galapagos NV, ImevaX GmbH, Nivalis Therapeutics, ProQR Therapeutics, PTI, Raptor Pharamceuticals, VRTX, Enterprise, Novartis, Pulmocide, Flately and Teva for advisory board and educational activities. She has received grant support from the CF Trust. TL has received personal fees from Alan Boyd Consultants, Ltd for his participation in DSMB activities. FAR has received personal consulting fees from Novartis, Bayer, Roche, and Genentech for participation in CF related consulting activities. He has received grant support to his institution from VRTX for his participation as site PI in multicenter trials which they have funded as well as personal consulting fees. MWK has received personal consulting fees for advisory board participation, grant support to his institution for clinical trial participation, and non-financial support from VRTX, Savara, Laurent, Corbus Pharmaceuticals, PTC, and AzurRx. He has received personal consulting fees and non-financial support from Chiesi, Celtaxsys, Merck, and Kala. Personal consulting fees were received from Albumedix, Paranta, Protalix, Santhera, pH Pharma, Novartis, Ionis, the Italian Cystic Fibrosis Foundation, and the Food and Drug Administration. Grant support was provided to his Institution by NIH. Grant support was provided to his Institution by Anthera as well as personal consulting fees. SCB has received support from VRTX, Galapagos, and AbbVie for his participation in advisory boards and as site PI in multicenter trials which they have funded. JLTC has received personal consulting fees from Gilead Sciences, Protalix, and Santhera for participation in advisory board activities. She has received grant support to her institution from PTI, Celtaxsys, and VRTX as well as personal consulting fees for advisory activities. Grant support to her institution for her participation as site PI in a multicenter trial which they have funded from Eloxx. KDB has received consulting fees from Boehringer-Ingelheim (BI), Protalix Biotherapeutics, Raptor Pharmaceuticals, Novabiotics, Eloxx Pharmaceutics, Galapagos, and Chiesi. She has received speaker fees from Teva Pharmaceutical Industries and serves on the Steering Committee and Advisory Board for VRTX. DGD has received consulting fees from VRTX and consulting fees as well as grant support from PTI and Chiesi. PAF has received personal consulting fees from the Food and Drug Administration, Polyphor, and Santhera. He has received personal consulting fees and grant support from CFF, PTI, Savara, and VRTX. He has received grant support from NIH, Novartis, Novoteris, and Sound Pharmaceuticals. PD has received personal consulting fees from VRTX, PTI, and Actelion Pharmaceuticals. He has also received support for his participation as site PI in multicenter trials funded by Corbus Pharmaceuticals and VRTX. CHG has received grant funding from CFF, NIH, the European Commission and the Food and Drug Administration. He has also received honoraria from Gilead Sciences for grant reviews, honoraria from VRTX and Mylan for invited talks, and BI for participation as a PI in a multicenter trial in CF that they have funded. IF has received consulting fees and support from PTI, VRTX and BI for her participation in advisory boards as well as site PI in multicenter trials which they have funded. She has received support from Corbus Pharmaceuticals for participation as site PI in multicenter trials which they have funded ASM has received grant support to her Institution from CFF. BSQ has received grant support to his institution from the Cystic Fibrosis Canada, CFF, Michael Smith Foundation for Health Research, BC Lung Association, and Gilead Sciences. GZRB's institution has received support from the CFF, NIH and VRTX. for his participation as site PI in multicenter trials which they have funded. AGD, KP, JPC, SHD, SMS, and JMVD have nothing to disclose., (Copyright © 2020. Published by Elsevier B.V.)

Background: Ataluren was developed for potential treatment of nonsense-mutation cystic fibrosis (CF). A previous phase 3 ataluren study failed to meet its primary efficacy endpoint, but post-hoc analyses suggested that aminoglycosides may have interfered with ataluren's action. Thus, this subsequent trial (NCT02139306) was designed to assess the efficacy and safety of ataluren in patients with nonsense-mutation CF not receiving aminoglycosides., Methods: Eligible subjects with nonsense-mutation CF (aged ≥6 years; percent predicted (pp) FEV 1 ≥40 and ≤90) from 75 sites in 16 countries were randomly assigned in double-blinded fashion to receive oral ataluren or matching placebo thrice daily for 48 weeks. The primary endpoint was absolute change in average ppFEV 1 from baseline to the average of Weeks 40 and 48., Findings: 279 subjects were enrolled; 138 subjects in the ataluren arm and 136 in the placebo arm were evaluable for efficacy. Absolute ppFEV 1 change from baseline did not differ significantly between the ataluren and placebo groups at Week 40 (-0.8 vs -1.8) or Week 48 (-1.7 vs -2.4). Average ppFEV 1 treatment difference from baseline to Weeks 40 and 48 was 0.6 (95% CI -1.3, 2.5; p = 0.54). Pulmonary exacerbation rate per 48 weeks was not significantly different (ataluren 0.95 vs placebo 1.13; rate ratio p = 0.40). Safety was similar between groups. No life-threatening adverse events or deaths were reported., Interpretation: Neither ppFEV 1 change nor pulmonary exacerbation rate over 48 weeks were statistically different between ataluren and placebo groups. Development of a nonsense-mutation CF therapy remains elusive., Competing Interests: Declaration of Competing Interest JM is an employee of PTC Therapeutics, the funder of this clinical trial, and holds financial interests in the company. MWK, SMR, and DRV received compensation for consultant services from PTC Therapeutics prior to and/or during this study. EK, MW, IS-G, and KDB received compensation for travel expenses for meetings related to the study. All other authors declare no competing interests., (Copyright © 2020. Published by Elsevier B.V.)

Antimicrobials have undoubtedly improved the lives of people with CF, but important antimicrobial-related toxicities and the emergence of antimicrobial-resistant bacteria associated with their use must be considered. Antimicrobial stewardship (AMS) is advocated across the spectrum of healthcare to promote the appropriate use of antimicrobials to preserve their current effectiveness and to optimise treatment, and it is clear that AMS strategies are applicable to and can benefit both non-CF and CF populations. This perspective explores the definition and components of an AMS program, the current evidence for AMS, and the reasons why AMS is a challenging concept in the provision of CF care. We also discuss the elements of CF care which align with AMS programs and principles and propose research priorities for AMS in CF., Competing Interests: Declaration of Competing Interest Drs. Kahl, Maples, Holmes and Muhlebach have nothing to disclose. Dr. Cogen reports grants from the Cystic Fibrosis Foundation outside of this work. Dr. McColley reports disclosures from Vertex Pharmaceuticals, Gilead Sciences, and grants from Northwestern University Clinical and Translational Sciences Institute outside of this work. Dr. Roberts reports grants and personal fees from MSD, grants from QPEX, personal fees from Discuva, personal fees from Accelerate Diagnostics, grants and personal fees from Biomerieux, grants and personal fees from Pfizer and grants from The Medicines Company outside of this work. Dr. Winthrop reports grants and personal fees from Pfizer, personal fees from AbbVie, personal fees from UCB, personal fees from Lilly, personal fees from Galapagos, personal fees from GSK, personal fees from Roche, personal fees from Gilead, grants from BMS, and grants from Insmed outside of this work. Dr. Morris reports and receives salary support from the Sinai Health and University Health Network in his role as Director of their Antimicrobial Stewardship Program. Dr. Flume reports grants outside of this submitted work from the European Cystic Fibrosis Society, the Cystic Fibrosis Foundation, Cystic Fibrosis Trust, Cystic Fibrosis Canada, Cystic Fibrosis Australia, and Novoteris. Dr. Flume also receives personal fees from Insmed outside this submitted work. Dr. VanDevanter reports personal fees from AbbVie, Albumedix, AN2, Aradigm, Armata, Arrevus, Calithera, Chiesi USA, Cipla, Corbus, Cystic Fibrosis Foundation, Eloxx, Enbiotix, Eveo, Galephar, Horizon, IBF, ICON clinical sciences, Ionis, Kala, Merck, Microbion, NDA, Protalix, PTC, Pulmocide, Recida, Savara, Vast, and Vertex outside of this work. Dr. Waters reports grants from Gilead and Astrazenca outside of this work. Dr. Elborn reports grants from Innovative Medicines Institute, Framework Seven, European Commission, Medical Research Council, and Bronch UK during the conduct of the study. Dr. Saiman reports grants from the CF Foundation, Merck, and AztraZeneca outside of this work. Dr. Bell reports grants and other support from Vertex, Galapagos and AbbVie outside of this work., (Copyright © 2020. Published by Elsevier B.V.)

Background: Antimicrobial susceptibility testing (AST) is a cornerstone of infection management in cystic fibrosis. However, there is little evidence that AST predicts the clinical outcome of CF antimicrobial treatment. It has been suggested there is a need for careful consideration of current AST use by the CF community., Methods: We engaged a group of experts consisting of pulmonary (adult and pediatric) and infectious disease clinicians, microbiologists, and pharmacists representing a broad international experience. We conducted an iterative systematic survey (Delphi) to determine and quantify consensus regarding key questions facing CF clinicians in the use of respiratory culture results including what tests to order, when to obtain them, and how to act upon the results of the testing., Results: Consensus was reached for many questions but there was not universal agreement to the questions that were addressed. There were some differences with respect to cultures obtained for surveillance compared to when there is clinical worsening. Areas of general consensus include when and how respiratory cultures should be performed, what information should be reported, and when AST should be performed. A key finding is that clinical response to treatment is used to guide treatment decisions rather than AST results., Conclusions: Recommendations are presented regarding questions related to microbiology testing for patients with CF. We have also offered recommendations for priority research questions., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019 European Cystic Fibrosis Society. All rights reserved.)

Background: In cystic fibrosis, observation of a lung function drop (as percent predicted forced expiratory volume in 1 s [FEV 1 ]; ppFEV 1 ) frequently precedes pulmonary exacerbation (PEx) diagnosis. Recovery of ppFEV 1 to a previous "baseline" is commonly used to assess antimicrobial treatment response. However, not all diagnosed PEx are associated with a ppFEV 1 drop, and it is unclear whether these are a different type of PEx from those associated with a ppFEV 1 drop., Methods: We analyzed pre- and posttreatment ppFEV 1 for PEx recorded in the Epidemiologic Study of Cystic Fibrosis from 2003 through 2005. Baseline, pretreatment, and follow-up ppFEV 1 were the best recorded within 12-months pre-PEx, the lowest recorded -30 to +3 days of treatment, and the best recorded during 6-month follow-up, respectively. Logistic regression models for return of ppFEV 1 to baseline during follow-up were developed separately for PEx with ≥10%, <10%, and no ppFEV 1 drop before treatment., Results: Of 15 147 PEx, 10 166 (67.1%), 3479 (23.0%), and 1502 (9.9%) presented with a ≥10%, <10%, or no ppFEV 1 drop at diagnosis, respectively. 19.5%, 35.2%, and 65.6% of PEx, respectively, had follow-up ppFEV 1 equal to or exceeding baseline; overall 27.7% of all PEx treatments resulted in complete recovery of baseline ppFEV 1 . Significant predictors of ppFEV 1 recovery at follow-up were younger patient age, absence of Aspergillus, lower baseline ppFEV 1 , fewer visits during the baseline, lower frequency of prior-year PEx, shorter elapsed time from baseline measure to treatment, smaller relative ppFEV 1 drop before treatment, and non intravenous (ie, oral or inhaled antibiotic) treatment. PEx with ≥10%, <10%, and no ppFEV 1 drop before treatment had only modest differences in covariate odds ratios associated with complete ppFEV 1 recovery., Conclusions: Among the 10% of PEx presenting with no apparent ppFEV 1 drop, more than one-third resulted in a decreased ppFEV 1 during follow-up. Risk factors for this outcome were the same as those associated with lack of ppFEV 1 recovery among PEx with pretreatment ppFEV 1 drops. These results suggest that inherent FEV 1 variability, baseline and follow-up sampling methodologies, ppFEV 1 regression to the mean, and underlying lung disease progression complicate this approach for assessing effects of PEx and treatment response., (© 2019 Wiley Periodicals, Inc.)

Objectives: Non-cystic fibrosis bronchiectasis (NCFBE) with Pseudomonas aeruginosa has been associated with increased pulmonary exacerbation (PEx) and mortality risk. European Respiratory Society guidelines conditionally recommend inhaled antimicrobials for persons with NCFBE, P aeruginosa and three or more PEx/year. We report microbiological results of two randomized, 48-week placebo-controlled trials of ARD-3150 (inhaled liposomal ciprofloxacin) in individuals with NCFBE with P aeruginosa and PEx history [Lancet Respir Med 2019;7:213-26]., Methods: Respiratory secretions from 582 participants receiving up to six 28-day on/off treatment cycles were analysed for sputum P. aeruginosa, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Escherichia coli densities, P. aeruginosa susceptibilities to ciprofloxacin and nine other antimicrobials, and prevalence of other bacterial opportunists. Associations between PEx risk and sputum density, antimicrobial susceptibility and opportunist prevalence changes were studied., Results: Sputum P. aeruginosa density reductions from baseline after ARD-3150 treatments ranged from 1.77 (95% CI 2.13-1.40) versus 0.54 (95% CI 0.89-0.19) log 10  CFU/g for placebo (second period) to 2.07 (95% CI 2.45-1.69) versus 0.70 (95% CI 1.11-0.29) log 10  CFU/g for placebo (fourth period) with only modest correlation between density reduction magnitude and PEx benefit. ARD-3150 (but not placebo) treatment was associated with increased P. aeruginosa ciprofloxacin MIC but not emergence of other bacterial opportunists across the study; ciprofloxacin MIC 50 increased from 0.5 to 1 mg/L, MIC 90 increased from 4 to 16 mg/L. Other antimicrobial MIC were mostly unaffected., Conclusion: Microbiological changes over 48 weeks of ARD-3150 treatment appear modest. Ciprofloxacin susceptibility (but not other antimicrobial susceptibility) decreases were observed that did not appear to preclude PEx risk reduction benefit., (Copyright © 2019 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Rationale: Differences in cystic fibrosis (CF) airway microbiota between periods of clinical stability and exacerbation of respiratory symptoms have been investigated in efforts to better understand microbial triggers of CF exacerbations. Prior studies have often relied on a single sample or a limited number of samples to represent airway microbiota. However, the variability in airway microbiota during periods of clinical stability is not well known. Objectives: To determine the temporal variability of measures of airway microbiota during periods of clinical stability, and to identify factors associated with this variability. Methods: Sputum samples ( N  = 527), obtained daily from six adults with CF during 10 periods of clinical stability, underwent sequencing of the V4 region of the bacterial 16S ribosomal RNA gene. The variability in airway microbiota among samples within each period of clinical stability was calculated as the average of the Bray-Curtis similarity measures of each sample to every other sample within the same period. Outlier samples were defined as samples outside 1.5 times the interquartile range within a baseline period with respect to the average Bray-Curtis similarity. Total bacterial load was measured with droplet digital polymerase chain reaction. Results: The variation in Bray-Curtis similarity and total bacterial load among samples within the same baseline period was greater than the variation observed in technical replicate control samples. Overall, 6% of samples were identified as outliers. Within baseline periods, changes in bacterial community structure occurred coincident with changes in maintenance antibiotics ( P  < 0.05, analysis of molecular variance). Within subjects, bacterial community structure changed between baseline periods ( P  < 0.01, analysis of molecular variance). Sample-to-sample similarity within baseline periods was greater with fewer interval days between sampling. Conclusions: During periods of clinical stability, airway bacterial community structure and bacterial load vary among daily sputum samples from adults with CF. This day-to-day variation has bearing on study design and interpretation of results, particularly in analyses that rely on single samples to represent periods of interest (e.g., clinical stability vs. pulmonary exacerbation). These data also emphasize the importance of accounting for maintenance antibiotic use and granularity of sample collection in studies designed to assess the dynamics of CF airway microbiota relative to changes in clinical state.

Background: Although antimicrobial susceptibility testing (AST) frequently guides cystic fibrosis (CF) pulmonary exacerbation (PEx) management, its clinical utility is unclear. This study examined associations between AST and antimicrobial switching during PEx treatment and time and occurrence of next PEx as treatment outcomes., Methods: This retrospective cohort study utilized Pediatric Health Information System data. Children and adolescents aged 1-18 years admitted for a PEx from 2011 to 2016 were studied. Antimicrobial switching was defined as any intra-admission change in intravenous (IV), oral, and/or inhaled antimicrobials. Time to next PEx was defined as the time between index PEx hospital discharge and subsequent hospital admission requiring IV antimicrobials. Odds of antimicrobial switching ≥5 days after treatment initiation were determined by generalized linear mixed models, and associations between AST and time to next PEx were studied using Kaplan-Meier curves and Cox proportional hazards regression., Results: AST occurred in 2518 (39%) of 6451 PEx at 36 hospitals and was associated with increased odds of antimicrobial switching (OR 1.33, 95% CI 1.16-1.52; p = 0.001) and increased hazard of future PEx (HR 1.32, 95% CI 1.16-1.50; p < 0.001). However, antimicrobial switching was not associated with a longer time to next PEx., Conclusions: AST was associated with both increased probability of antimicrobial regimen change and increased PEx hazard. There was no evidence that antimicrobial regimen change was associated with clinical benefit as assessed by time to next PEx. However, these results indicate residual indication bias remained after adjustment for available disease covariates. Additional studies of the clinical value of AST are warranted., (Copyright © 2019 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Median cystic fibrosis (CF) survival has increased dramatically over time due to several factors, including greater availability and use of antimicrobial therapies. During the progression of CF lung disease, however, the emergence of multidrug antimicrobial resistance can limit treatment effectiveness, threatening patient longevity. Current planktonic-based antimicrobial susceptibility testing lacks the ability to predict clinical response to antimicrobial treatment of chronic CF lung infections. There are numerous reasons for these limitations including bacterial phenotypic and genotypic diversity, polymicrobial interactions, and impaired antibiotic efficacy within the CF lung environment. The parallels to other chronic diseases such as non-CF bronchiectasis are discussed as well as research priorities for moving forward., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Antimicrobial susceptibility testing (AST) is a cornerstone of infection management. Cystic fibrosis (CF) treatment guidelines recommend AST to select antimicrobial treatments for CF airway infection but its utility in this setting has never been objectively demonstrated., Methods: We conducted a systematic review of primary published articles designed to address two PICO (patient, intervention, comparator, outcome) questions: 1) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection predictable from AST results available at treatment initiation?" and 2) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection affected by the method used to guide antimicrobial selection?" Relationships between AST results and clinical response (changes in pulmonary function, weight, signs and symptoms of respiratory tract infection, and time to next event) were assessed for each article and results were compared across articles when possible., Results: Twenty-five articles describing the results of 20 separate studies, most of which described Pseudomonas aeruginosa treatment, were identified. Thirteen studies described pulmonary exacerbation (PEx) treatment and seven described 'maintenance' of chronic bacterial airways infection. In only three of 16 studies addressing PICO question #1 was there a suggestion that baseline bacterial isolate antimicrobial susceptibility was associated with clinical response to treatment. None of the four studies addressing PICO question #2 suggested that antimicrobial selection methods influenced clinical outcomes., Conclusions: There is little evidence that AST predicts the clinical outcome of CF antimicrobial treatment, suggesting a need for careful consideration of current AST use by the CF community., (Copyright © 2019 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Background: New drugs that improve the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein with discreet disease-causing variants have been successfully developed for cystic fibrosis (CF) patients. Preclinical model systems have played a critical role in this process, and have the potential to inform researchers and CF healthcare providers regarding the nature of defects in rare CFTR variants, and to potentially support use of modulator therapies in new populations., Methods: The Cystic Fibrosis Foundation (CFF) assembled a workshop of international experts to discuss the use of preclinical model systems to examine the nature of CF-causing variants in CFTR and the role of in vitro CFTR modulator testing to inform in vivo modulator use. The theme of the workshop was centered on CFTR theratyping, a term that encompasses the use of CFTR modulators to define defects in CFTR in vitro, with application to both common and rare CFTR variants., Results: Several preclinical model systems were identified in various stages of maturity, ranging from the expression of CFTR variant cDNA in stable cell lines to examination of cells derived from CF patients, including the gastrointestinal tract, the respiratory tree, and the blood. Common themes included the ongoing need for standardization, validation, and defining the predictive capacity of data derived from model systems to estimate clinical outcomes from modulator-treated CF patients., Conclusions: CFTR modulator theratyping is a novel and rapidly evolving field that has the potential to identify rare CFTR variants that are responsive to approved drugs or drugs in development., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Antimicrobial resistance (AMR) can present significant challenges in the treatment of cystic fibrosis (CF) lung infections. In CF and other chronic diseases, AMR has a different profile and clinical consequences compared to acute infections and this requires different diagnostic and treatment approaches. This review defines AMR, explains how it occurs, describes the methods used to measure AMR as well as their limitations, and concludes with future directions for research and development in the area of AMR in CF., (Copyright © 2018 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Background: Chronic Pseudomonas aeruginosa (Pa) airways infection, exuberant local inflammation, and progressive lung function loss are hallmarks of cystic fibrosis (CF). KB001-A is an anti-PcrV PEGylated monoclonal antibody fragment to the Type III secretion system of Pa. This 16-week study evaluated KB001-A associated effect on time-to-need for antibiotics for worsening respiratory signs and symptoms, as well as safety, and treatment-associated changes in symptom scores, inflammatory markers, and spirometry., Methods: This was a randomized, double-blind, placebo-controlled, repeat-dose study in CF subjects with Pa. Intravenous 10mg/kg KB001-A or placebo infusions were administered at baseline and weeks 2, 4, 8, and 16, with a 4-week follow-up. Sputum inflammatory markers were assessed in a sub-study. Time-to-need for antibiotics was compared between groups by Kaplan Meier analysis and Cox proportional hazards modeling adjusting for randomization strata., Results: Of 182 subjects, 169 received at least one infusion of KB001-A (n=83) or placebo (n=86). KB001-A was generally safe and well-tolerated as compared to placebo, with no significant emergent adverse effects other than one serious adverse event of elevated hepatic enzymes of unclear etiology. Time to need for antibiotics did not differ between groups (HR: 1.00; 95% CI: 0.69, 1.45, p=0.995). A 3.2 increase in ppFEV 1 from placebo favoring KB001-A was observed at week 16 (95% CI: 1.12, 5.30, p=0.003). Mean changes from baseline in log 10 sputum neutrophil elastase (NE) had a non-significant decrease (-0.27, 95% CI: -0.58,0.04, p=0.084) while IL-8 concentrations at week 16 were significantly lower (-0.27, 95% CI: -0.55,0.00, p=0.048) among KB001-A subjects (n=16) relative to placebo (n=13)., Conclusions: KB001-A was safe and well-tolerated and associated with a modest FEV 1 benefit and reduction in select sputum inflammatory markers (IL-8). KB001-A was not associated with an increased time to need for antibiotics. The lack of efficacy seen with KB001-A may be due, in part, to the low levels of the type III secretion proteins previously reported in sputum of CF patients chronically infected with Pa., (Copyright © 2017 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Rationale: Cystic fibrosis deaths result primarily from lung function loss, so chronic respiratory therapies, intended to preserve lung function, are cornerstones of cystic fibrosis care. Although treatment-associated reduction in rate of lung function loss should ultimately improve cystic fibrosis survival, no such relationship has been described for any chronic cystic fibrosis therapy. In part, this is because the ages of most rapid lung function decline-early adolescence-precede the median age of cystic fibrosis deaths by more than a decade., Objectives: To study associations of high-dose ibuprofen treatment with the rate of forced expiratory volume in 1 second decline and mortality among children followed in the Epidemiologic Study of Cystic Fibrosis and subsequently in the U.S. Cystic Fibrosis Foundation Patient Registry., Methods: We performed a matched cohort study using data from Epidemiologic Study of Cystic Fibrosis. Exposure was defined as high-dose ibuprofen use reported at ≥80% of encounters over 2 years. Unexposed children were matched to exposed children 5:1 using propensity scores on the basis of demographic, clinical, and treatment covariates. The rate of decline of percent predicted forced expiratory volume in 1 second during the 2-year follow-up period was estimated by mixed-effects modeling with random slopes and intercepts. Survival over 16 follow-up years in the U.S. Cystic Fibrosis Foundation Patient Registry was compared between treatment groups by using proportional hazards modeling controlling for matching and covariates., Results: We included 775 high-dose ibuprofen users and 3,665 nonusers who were well matched on demographic, clinical, and treatment variables. High-dose ibuprofen users declined on average 1.10 percent predicted forced expiratory volume in 1 second/yr (95% confidence interval; 0.51, 1.69) during the 2-year treatment period, whereas nonusers declined at a rate of 1.76% percent predicted forced expiratory volume in 1 second/yr (95% confidence interval; 1.48, 2.04) during the corresponding 2-year period, a 37.5% slower decline among users compared with nonusers (95% confidence interval; 0.4%, 71.3%; P = 0.046). The users had better subsequent survival (P < 0.001): the unadjusted and adjusted hazard ratios for mortality (high-dose ibuprofen/non-high-dose ibuprofen) (95% confidence interval) were 0.75 (0.64, 0.87) and 0.82 (0.69, 0.96)., Conclusions: In a propensity-score matched cohort study of children with cystic fibrosis, we observed an association between high-dose ibuprofen use and both slower lung function decline and improved long-term survival. These results are consistent with the hypothesis that treatment-associated reduction of lung function decline in children with cystic fibrosis leads to improved survival.

Bacteria that infect the airways of persons with cystic fibrosis (CF) include a group of well-described opportunistic pathogens as well as numerous, mainly obligate or facultative anaerobic species typically not reported by standard sputum culture. We sequenced the V3-V5 hypervariable region of the bacterial 16S rRNA gene in DNA derived from 631 sputum specimens collected from 111 CF patients over 10 years. We describe fluctuations in the relative abundances of typical CF pathogens, as well as anaerobic species, in relation to changes in patients' clinical state and lung disease stage. Both bacterial community diversity and the relative abundance of anaerobes increased during exacerbation of symptoms (prior to antibiotic treatment), although this trend was not observed uniformly across disease stages. Community diversity and the relative abundance of anaerobic species decreased during antibiotic treatment. These results support current hypotheses regarding the role of anaerobes in CF pulmonary exacerbations and lung disease progression.

Rationale: There are important gaps in knowledge of the optimal treatment of cystic fibrosis pulmonary exacerbations. Previous observational studies comparing inpatient with outpatient treatment have suffered from methodologic weaknesses, especially indication bias., Objectives: We analyzed data from the Epidemiologic Study of Cystic Fibrosis using techniques to control for indication bias to determine whether there is an advantage to inpatient treatment of cystic fibrosis pulmonary exacerbations., Methods: We identified typical pulmonary exacerbations in patients ages 6 years and older during the 3-year observation period ending in 2005. In our primary analysis, we used the instrumental variables method, implemented using two-stage least squares regression, to evaluate the effect of the proportion of total time that intravenous treatment was administered on an inpatient (versus outpatient) basis on the likelihood of return of percent predicted forced expiratory volume in 1 second to greater than or equal to 90% of baseline post-treatment. We also evaluated two other indicators of treatment setting, three other measures of treatment response, and two alternative modeling techniques, and we also looked for differences between children and adults., Results: Our final analysis included 4,497 pulmonary exacerbations in 2,773 individual patients at 75 sites. We calculated the mean proportion of intravenous treatment time that was provided in the hospital setting at each site. The median across sites was 0.581 (interquartile range, 0.396-0.753). The median treatment success rate across sites was 74.2% (interquartile range, 67.9 to 79.2%). Univariate analysis and two-stage least squares models showed a positive relationship between treatment success and proportion of inpatient treatment days. Our primary model revealed an absolute increase of 9.08% (95% confidence interval, 2.55-15.61; P = 0.006) in the achievement of a return of percent predicted forced expiratory volume in 1 second to greater than or equal to 90% of baseline comparing complete inpatient treatment with no inpatient treatment. Treatment response was not related to duration of intravenous therapy. Similar results were found for all our modeling techniques and outcomes., Conclusions: Patients with cystic fibrosis treated at sites with more reliance on inpatient treatment were more likely to achieve successful forced expiratory volume in 1 second recovery. There was no relationship between treatment duration and recovery of forced expiratory volume in 1 second.

Background: Pulmonary exacerbations (PEx) in cystic fibrosis (CF) are common and contribute to morbidity and mortality. Duration of IV antibiotic therapy to treat PEx varies widely in the US, and there are few data to guide treatment decisions., Methods: We combined a survey of CF stakeholders with retrospective analyses of a recent observational study of CF PEx to design a multicenter, randomized, prospective study comparing the efficacy and safety of different durations of IV antibiotics for PEx to meet the needs of people with CF and their caregivers., Results: IV antibiotic duration was cited as the most important PEx research question by responding CF physicians and top concern among surveyed CF patients/caregivers. During PEx, forced expiratory volume in 1s (FEV 1 % predicted) and symptom responses at 7-10days of IV antibiotics identified two distinct groups: early robust responders (ERR) who subsequently experienced greater FEV 1 improvements compared to non-ERR (NERR). In addition to greater FEV 1 and symptom responses, only 14% of ERR patients were treated with IV antibiotics for >15days, compared with 45% of NERR patients., Conclusions: A divergent trial design that evaluates subjects' interim improvement in FEV 1 and symptoms to tailor randomization to IV treatment duration (10 vs. 14days for ERR, 14 vs. 21days for NERR) may alleviate physician and patient concerns about excess or inadequate treatment. Such a study has the potential to provide evidence necessary to standardize IV antibiotic duration in CF PEx care -a first step to conducting PEx research of other treatment features., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: When the chronic respiratory therapy dornase alfa was made commercially available for cystic fibrosis (CF) more than 20 years ago, two regimens were approved: 2.5 mg inhaled once daily (QD) or twice daily (BID). In the intervening years, there has been little guidance as to when to use each regimen. We have studied clinical practice patterns captured in the Epidemiologic Study of CF (ESCF) during the decade following dornase alfa approval (1994-2005) to better understand clinical characteristics associated with QD versus BID dornase alfa use. Methods We studied the characteristics of ESCF patients who received either dornase alfa regimen for at least 12 months and who were then switched to the alternate regimen for at least 6 months and who had adequate data available around the time of the switch. Average lung function and weight-for-age (WFA) z-scores, numbers of intravenous (IV) antibiotic-treated pulmonary exacerbations, and prevalence of signs and symptoms were determined for 6-month periods capturing the beginning (FIRST) and the end (LAST) of the initial regimen, the 6 months preceding the final 6 months of the initial regimen (PRIOR), and the beginning of the second regimen (POST). Changes in values from FIRST to LAST, PRIOR to LAST, and LAST to POST were studied to better understand clinical scenarios associated with decisions to change regimens., Results: A total of 1342 QD and 574 BID regimens were studied with median durations of 3.19 and 2.09 years, respectively. On average, patients beginning BID regimens had worse lung function and a greater number of pulmonary exacerbations treated with IV antibiotics than those beginning QD regimens. However, by the time of regimen switch, patients switching from QD to BID dornase alfa had experienced substantial deterioration with respect to pulmonary exacerbations and signs and symptoms, whereas patients switching from BID to QD had not. Interestingly, incidence of IV-treated pulmonary exacerbations and signs and symptom prevalence decreased for both populations after regimen switch., Conclusions: We have studied populations of patients with CF receiving dornase alfa who were switched between regimens to characterize clinical course. Our results suggest that the most common clinical attribute associated with switching from QD to BID dornase alfa was a marked deterioration in stability characterized by increased incidence and frequency of pulmonary exacerbation. For this population, deterioration in lung function did not appear to be a driver for this switch. In contrast, patients receiving BID dornase alfa who were ultimately switched to QD appeared to be clinically stable, on average, suggesting that treatment burden and cost may have been drivers of the decision to switch regimens., (© 2017 Wiley Periodicals, Inc.)