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People in prison are at high risk of HCV given high injecting drug use prevalence. This study evaluated HCV incidence and associated injecting drug use characteristics in prison. The SToP-C study enrolled people incarcerated in four Australian prisons. Participants were tested for HCV at enrolment and then every 3-6 months (October-2014 to November-2019). Participants eligible for this analysis included those at-risk of HCV primary infection (anti-HCV negative) or re-infection (anti-HCV positive, HCV RNA negative) with follow-up assessment. A total of 1643 eligible participants were included in analyses (82% male; median age 33 years; 30% injected drugs in prison; 1818 person-years of follow-up). Overall HCV incidence was 6.11/100 person-years (95%CI: 5.07-7.35), with higher rate of re-infection (9.34/100 person-years; 95%CI: 7.15-12.19) than primary infection (4.60/100 person-years; 95%CI: 3.56-5.96). In total population (n = 1643), HCV risk was significantly higher among participants injecting drugs in prison [vs. no injecting; adjusted hazard ratio (aHR): 10.55, 95%CI: 5.88-18.92), and those who were released and re-incarcerated during follow-up (vs. remained incarcerated; aHR: 1.60, 95%CI: 1.03-2.49). Among participants who injected recently (during past month, n = 321), HCV risk was reduced among those receiving high-dosage opioid agonist therapy (OAT), i.e. methadone ≥60 mg/day or buprenorphine ≥16 mg/day, (vs. no OAT, aHR: 0.11, 95%CI: 0.02-0.80) and increased among those sharing needles/syringes without consistent use of disinfectant to clean injecting equipment (vs. no sharing, HR: 4.60, 95%CI: 1.35-15.66). This study demonstrated high HCV transmission risk in prison, particularly among people injecting drugs. High-dosage OAT was protective, but improved OAT coverage and needle/syringe programmes to reduce sharing injecting equipment are required., (© 2023 The Authors. Journal of Viral Hepatitis published by John Wiley & Sons Ltd.)

Objective: Reinfection poses a challenge to hepatitis C virus (HCV) elimination. This analysis assessed incidence of, and factors associated with reinfection among people treated for recent HCV (duration of infection <12 months)., Methods: Participants treated for recent HCV (primary infection or reinfection) in an international randomized trial were followed at 3-monthly intervals for up to 2 years to assess for reinfection. Reinfection incidence was calculated using person-time of observation. Factors associated with HCV reinfection were assessed using Cox proportional hazards regression analysis., Results: Of 222 participants treated for recent HCV, 196 (62% primary infection, 38% reinfection) were included in the cohort at risk for reinfection, of whom 87% identified as gay or bisexual men, 71% had HIV and 20% injected drugs in the month prior to enrolment. During 198 person-years of follow-up, 28 cases of HCV reinfection were identified among 27 participants, for an incidence of 14.2 per 100 person-years [95% confidence interval (CI) 9.8-20.5]. Reinfection was associated with prior HCV reinfection [adjusted hazards ratio (aHR) 2.42; 95% CI 1.08-5.38], injection drug use posttreatment (aHR 2.53; 95% CI 1.14-5.59), condomless anal intercourse with casual male partners (aHR 3.32; 95% CI 1.14-9.65) and geographic region (United Kingdom, aHR 0.21; 95% CI 0.06-0.75). Among gay and bisexual men (GBM), reinfection was also associated with sexualized drug use involving injecting posttreatment (aHR 2.97; 95% CI 1.10-8.02)., Conclusion: High reinfection incidence following treatment for recent HCV among people with ongoing sexual and drug use risk behaviour highlights the need for posttreatment surveillance, rapid retreatment of reinfection and targeted harm reduction strategies., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Exploration of sexual and drug use behaviours following treatment for recent hepatitis C virus (HCV) is limited. This analysis modelled behavioural trajectories following treatment for recent HCV and assessed reinfection., Methods: Participants treated for recent HCV in an international trial (enrolled 2017-2019) were followed at 3-monthly intervals for up to 2 years to assess longitudinal behaviours. Population-averaged changes were assessed using generalized estimating equations. Distinct behavioural trajectories were identified using group-based trajectory modelling. HCV reinfection incidence was calculated using person-years (PY) of observation., Results: During the follow-up of 212 participants (84% gay and bisexual men [GBM]; 69% HIV; 26% current injecting drug use [IDU]), behavioural trajectories for IDU and stimulant use (past month) did not change. However, population-averaged decreases in the likelihood of daily IDU (adjusted odds ratio [AOR] 0.83; 95% CI 0.72, 0.95) and opioid use (AOR 0.84; 95% CI 0.75, 0.93) were observed. Among GBM, behavioural trajectories for chemsex did not change. Population-averaged decreases in condomless anal intercourse with casual male partners (CAI-CMP) (AOR 0.95; 95% CI 0.90, 0.99) and group-sex (AOR 0.86; 95% CI 0.80, 0.93) were observed, but masked distinct trajectories. While a proportion had a decreased probability of CAI-CMP (23%) and group-sex (59%) post-treatment, a substantial proportion retained a high probability of these behaviours. High HCV reinfection incidence was observed for the sustained high probability IDU (33.0/100 PY; 95% CI 17.7, 61.3) and chemsex (23.3/100 PY; 95% CI 14.5, 37.5) trajectories., Conclusions: Limited sexual and drug use behavioural change was observed following treatment for recent HCV, supporting access to surveillance and (re)treatment., (© 2023 The Authors. Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of the International AIDS Society.)

Background: People experiencing homelessness are disproportionately affected by hepatitis C virus (HCV) infection compared with housed populations. Surveillance for HCV reinfection after successful treatment is a critical step in the care cascade, but limited data on reinfection are available among this highly marginalized group. This study assessed posttreatment reinfection risk in a real-world cohort of homeless-experienced individuals in Boston., Methods: Individuals receiving HCV direct-acting antiviral treatment through Boston Health Care for the Homeless Program during 2014-2020 with posttreatment follow-up assessment were included. Reinfection was identified based on recurrent HCV RNA at 12 weeks posttreatment with HCV genotype switch or any recurrent HCV RNA following sustain virologic response., Results: A total of 535 individuals were included (81% male, median age 49 years, 70% unstably housed or homeless at treatment initiation). Seventy-four HCV reinfections were detected, including 5 second reinfections. HCV reinfection rate was 12.0/100 person-years (95% confidence interval [CI]: 9.5-15.1) overall, 18.9/100 person-years (95% CI: 13.3-26.7) among individuals with unstable housing and 14.6/100 person-years (95% CI: 10.0-21.3) among those experiencing homelessness. In adjusted analysis, experiencing homelessness (vs stable housing, adjusted hazard ratio, 2.14; 95% CI: 1.09-4.20; P = .026) and drug use within 6 months before treatment (adjusted hazard ratio, 5.23; 95% CI: 2.25-12.13; P < .001) were associated with increased reinfection risk., Conclusions: We found high HCV reinfection rates in a homeless-experienced population, with increased risk among those homeless at treatment. Tailored strategies to address the individual and systems factors impacting marginalized populations are required to prevent HCV reinfection and to enhance engagement in posttreatment HCV care., Competing Interests: Potential conflicts of interest . M. E. B., S. K. S., and L. C. S. report payment or honoraria received from New England AIDS Education and Training Center. M. E. B. also reports an unpaid position on the Steering Committee for EndHepCMA. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background & Aims: Population-level uptake of direct-acting antiviral (DAA) treatment for hepatitis C virus (HCV) infection, including retreatment, can be estimated through administrative pharmaceutical dispensation data. However, the reasons for retreatment are not captured in these data. We developed a machine learning model to classify retreatments as reinfection or treatment failure at a national level., Methods: Retreatment data from the REACH-C cohort (n = 10,843 treated with DAAs; n = 320 retreatments with known reason), were used to train a random forest model. Nested cross validation was undertaken to assess model performance and to optimise hyperparameters. The model was applied to data on DAA retreatment dispensed during 2016-2021 in Australia, to identify the reason for retreatment (treatment failure or reinfection)., Results: Average predictive accuracy, precision, sensitivity, specificity and F 1 -score for the model were 96.3%, 96.5%, 96.3%, 96.3% and 96.3%, respectively. Nationally, 95,272 individuals initiated DAAs, with treatment uptake declining from 32,454 in 2016 to 6,566 in 2021. Of those treated, 6,980 (7%) were retreated. Our model classified 51.8% (95% CI 46.7-53.6%; n = 3,614) of cases as reinfection and 48.2% (95% CI 46.4-53.3%; n = 3,366) as treatment failure. Retreatment for reinfection increased steadily over the study period from 14 in 2016 to 1,092 in 2020, stabilising in 2021. Retreatment for treatment failure increased from 73 in 2016 to 1,077 in 2019, then declined to 515 in 2021. Among individuals retreated for treatment failure, 50% had discontinued initial treatment., Conclusions: We used a novel methodology with high classification accuracy to evaluate DAA retreatment patterns at a national level. Increases in retreatment uptake for treatment failure corresponded to the availability of pangenotypic and salvage regimens. Increasing retreatment uptake for reinfection likely reflects increasing reinfection incidence., Impact and Implications: This study used machine learning methodologies to analyse national administrative data and characterise trends in HCV retreatment due to reinfection and treatment failure. Retreatment for reinfection increased over time, reflecting increasing numbers of people at risk for reinfection following HCV cure. Increased retreatment for treatment failure corresponded to the availability of pangenotypic and salvage DAA regimens. The findings of this study can be used by public health agencies and policy makers to guide and assess HCV elimination strategies, while the novel methodology for monitoring trends in HCV retreatment has the potential to be used in other settings, and health conditions., (Copyright © 2022 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background: Injection drug use (IDU) following treatment for hepatitis C virus (HCV) infection may lead to reinfection, particularly if access to harm reduction services is suboptimal. This study assessed HCV reinfection risk following direct-acting antiviral therapy within Australian prisons that had opioid agonist therapy (OAT) programs but did not have needle and syringe programs (NSPs)., Methods: The Surveillance and Treatment of Prisoners With Hepatitis C (SToP-C) study enrolled people incarcerated in 4 prisons between 2014 and 2019. Participants treated for HCV were followed every 3-6 months to identify reinfection (confirmed by sequencing). Reinfection incidence and associated factors were evaluated., Results: Among 388 participants receiving treatment, 161 had available posttreatment follow-up and were included in analysis (92% male; median age, 33 years; 67% IDU in prison; median follow-up 9 months). Among those with recent (in the past month) IDU (n = 71), 90% had receptive needle/syringe sharing. During 145 person-years (PY) of follow-up, 18 cases of reinfection were identified. Reinfection incidence was 12.5/100 PY (95% confidence interval [CI]: 7.9-19.8) overall, increasing to 28.7/100 PY (95% CI: 16.3-50.6) among those with recent IDU and needle/syringe sharing. In adjusted analysis, recent IDU with needle/syringe sharing was associated with increased reinfection risk (adjusted hazard ratio [aHR], 4.74 [95% CI: 1.33-16.80]; P = .016) and longer HCV testing interval with decreased risk (ie, chance of detection; aHR, 0.41 per each month increase [95% CI: .26-.64]; P < .001)., Conclusions: A high rate of HCV reinfection was observed within prison. Posttreatment surveillance and retreatment are -essential to limit the impact of reinfection. High-coverage OAT and NSPs should be considered within prisons., Clinical Trials Registration: NCT02064049., Competing Interests: Potential conflicts of interest. A. R. L. and G. J. D. were supported by NHMRC Practitioner Fellowships. J. G. was supported by an NHMRC Investigator Grant. E. C. is supported by a postdoctoral fellowship from the Canadian Network on Hepatitis C. P. V. acknowledges support from the US National Institute on Drug Abuse (NIDA; grant numbers R01AI147490, R01DA033679, R01DA037773, R21DA046809, and R01DA047952); the National Institute for Health Research (NIHR) Health Protection Research Unit in Evaluation of Interventions and Behavioral Science at the University of Bristol; and the NIHR-funded EPIToPe project. N. K. M. acknowledges support from the US National Institute of Allergy and Infectious Diseases and NIDA (grant number R01AI147490), and the University of California, San Diego Center for AIDS Research, a program funded by the US National Institutes of Health (grant number P30 AI036214). C. T. reports research funds, unrelated to this project, paid to the institution from Merck, and speaker’s fees from AbbVie and Gilead. G. J. D. reports research grants outside the submitted work from AbbVie, Gilead Sciences, and Merck. G. V. M. reports research grants from AbbVie and Gilead, outside the submitted work, and payment or honoraria from Janssen (speaker’s bureau) and AstraZeneca (advisory board). J. G. reports grants or contracts outside the submitted work from AbbVie, Camurus, Cepheid, Hologic, Indivior, and Merck and payment or honoraria from AbbVie, Cepheid, Gilead Sciences, and Merck. N. K. M. reports unrestricted research grants to the university unrelated to this research from Gilead and Merck. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Australia was one of the first countries with unrestricted access to government subsidized direct-acting antiviral (DAA) therapy for adults with chronic hepatitis C virus. This study assessed real-world DAA treatment outcomes across a diverse range of Australian clinical services and evaluated factors associated with successful treatment and loss to follow-up. Real-world Effectiveness of Antiviral therapy in Chronic Hepatitis C (REACH-C) consisted a national observational cohort of 96 clinical services including specialist clinics and less traditional settings such as general practice. Data were obtained on consecutive individuals who commenced DAAs from March 2016 to June 2019. Effectiveness was assessed by sustained virological response ≥12 weeks following treatment (SVR) using intention-to-treat (ITT) and per-protocol (PP) analyses. Within REACH-C, 10,843 individuals initiated DAAs (male 69%; ≥50 years 52%; cirrhosis 22%). SVR data were available in 85% (9,174 of 10,843). SVR was 81% (8,750 of 10,843) by ITT and 95% (8,750 of 9,174) by PP. High SVR (≥92%) was observed across all service types and participant characteristics. Male gender (adjusted odds ratio [aOR] 0.56, 95% confidence interval [CI] 0.43-0.72), cirrhosis (aOR 0.52, 95% CI 0.41-0.64), recent injecting drug use (IDU; aOR 0.64, 95% CI 0.46-0.91) and previous DAA treatment (aOR 0.50, 95% CI 0.28-0.90) decreased the likelihood of achieving SVR. Multiple factors modified the likelihood of loss to follow-up including IDU ± opioid agonist therapy (OAT; IDU only: aOR 1.75, 95% CI 1.44-2.11; IDU + OAT: aOR 1.39, 95% CI 1.11-1.74; OAT only, aOR 1.36; 95% CI 1.13-1.68) and age (aOR 0.97, 95% CI 0.97-0.98). Conclusion: Treatment response was high in a diverse population and through a broad range of services following universal access to DAA therapy. Loss to follow-up presents a real-world challenge. Younger people who inject drugs were more likely to disengage from care, requiring innovative strategies to retain them in follow-up., (© 2021 The Authors. Hepatology Communications published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Background: Direct acting antiviral (DAA) therapy is highly effective for hepatitis C virus (HCV) infection, but reinfection following treatment may compromise benefits of cure. This study assessed the real-world effectiveness of treatment for reinfection., Methods: Real-world effectiveness of antiviral therapy in chronic hepatitis C (REACH-C) is an observational study evaluating treatment outcomes following sequential DAA initiations across 33 health services in Australia between March 2016-June 2019. Reinfection was defined by post-treatment genotype switch or HCV viraemia after sustained virologic response (SVR12)., Results: Of the 10,843 individuals initiating DAA therapy post-treatment viraemia was reported in 526 of whom 99 were reinfections. Treatment for reinfection occurred in 88 individuals. In those with available treatment outcomes, SVR12 was similar to initial treatment in the overall REACH-C cohort (95% vs 95%; p = 0.745) and comparable across primary, tertiary, and prison settings. Classifying unknown treatment outcomes as failures, SVR12 for treatment of reinfection was lower than initial treatment in REACH-C (67% vs 81%; p = 0.002), due to higher lost to follow-up., Conclusions: Treatment of reinfection is highly effective and can be delivered in non-specialist settings. Access to treatment for reinfection in high-risk populations is crucial to HCV elimination., Competing Interests: Declarations of Interest GVM reports grants from Gilead Sciences and grants from AbbVie. GJD reports grants, personal fees, and nonfinancial support from AbbVie, Gilead, Merck, Bristol-Myers Squibb, and Roche; grants and personal fees from Janssen; personal fees and nonfinancial support from Gilead Sciences; and personal fees from GlaxoSmithKline and Abbott Diagnostics. DI reports fees from Gilead, Merck, BMS, and AbbVie. PR reports fees for educational talks from Gilead Sciences, Merck Sharp & Dohme, and AbbVie and is on the advisory board for Merck Sharp & Dohme. AB reports sponsorship from Gilead to participate in online HCV medical educational modules. JDo reports grants to his institution for investigator initiated research and consulting fees from Gilead Sciences, Merck/MSD, AbbVie and Bristol-Myers Squibb. JO reports speaker fees from Gilead and BMS. MM reports grants from Gilead Sciences. JC/JY/BH/JH/JDa/PM report none., (Copyright © 2021. Published by Elsevier B.V.)