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Observational studies are often considered unreliable for evaluating relative treatment effectiveness, but it has been suggested that following target trial protocols could reduce bias. Using observational data from patients with rheumatoid arthritis (RA) in the Swedish Rheumatology Quality Register (SRQ), between 2006 and 2020, we emulated the protocol of the Swedish Farmacotherapy trial (SWEFOT) and compared the results. SWEFOT was a pragmatic trial nested in SRQ, between 2002 and 2005, where methotrexate (MTX) insufficient responders were randomized to receive additional infliximab or sulfasalazine (SSZ) + hydroxychloroquine (HCQ). Patients with RA initiating infliximab (N = 313) or SSZ + HCQ (N = 196) after MTX were identified in SRQ and the Prescribed Drugs Register, mimicking the SWEFOT eligibility criteria. The primary outcome was the proportion of European Alliance of Associations for Rheumatology (EULAR) good responders at 9 months, classifying patients who discontinued treatment as "nonresponders." Through sensitivity analyses, we assessed the impact of relaxing eligibility criteria. The observed proportions reaching EULAR good response were close to those reported in SWEFOT: 39% (vs. 39% in SWEFOT) for infliximab and 28% (vs. 25%) for SSZ + HCQ. The crude observed response ratio was 1.39 (95% confidence interval (CI) 1.04-1.86), increasing to 1.48 (95% CI 0.98-2.24) after confounding adjustment, compared to 1.59 (95% CI 1.10-2.30) in SWEFOT. Results remained close to SWEFOT when relaxing eligibility criteria until allowing prior disease-modifying anti-rheumatic drug (DMARD) use which reduced the observed difference between treatments. By applying a prespecified trial emulation protocol to observational clinical registry data, we could replicate the results of SWEFOT, favoring infliximab over SSZ + HCQ combination therapy at 9 months.

ObjectiveObservational studies have reported an increased risk of infections associated with glucocorticoids in RA, not supported by evidence from randomized controlled trials. Inappropriately accommodating time-varying exposure and confounding in observational studies might explain the conflicting results. Therefore, we compared the incidence of serious infections between different oral glucocorticoid dose patterns over three years in a prospective inception cohort, adjusting for time-varying confounders in marginal structural models.MethodsWe included 9654 newly diagnosed RA patients from the Swedish Rheumatology Quality Register between 2007–2018 and followed them for three years after the first rheumatology visit. Follow-up was divided into 90-day periods. A mean oral prednisone daily dose was calculated for each period and categorized into ‘no use’, ‘low’ (≤10 mg/day) and ‘high’ (>10 mg/day) doses. The incidence of serious infections (hospitalization for infection) over follow-up periods was modelled by pooled logistic regression allowing separate effects for recent and past exposure.ResultsAn increased incidence of serious infections was associated with higher compared with lower doses and with more recent compared with past glucocorticoid exposure. Over 3 years of follow-up, the marginal structural models predicted one additional serious infection for every 83 individuals treated with low GC doses for the first 6 months, and for every 125 individuals treated with high GC doses for the first 3 months, compared with no GC use.ConclusionOur results broadly agree with previous observational studies showing a dose dependent increased risk of infection associated with (recent) use of oral glucocorticoids.

Objectives To describe the use of baricitinib and tofacitinib by Swedish RA patients and to compare their effectiveness with that of biologic DMARDs (bDMARDs). Methods RA patients who initiated baricitinib (n = 1420), tofacitinib (n = 316), abatacept (n = 1050), IL-6 inhibitors (IL-6is; n = 849), rituximab (n = 1101) or TNF inhibitors (TNFis; n = 6036) between January 2017 and November 2019 were followed for a minimum of 1 year using data from several linked Swedish national registers. Proportions reaching a good EULAR 28-joint DAS (DAS28) response, HAQ Disability Index (HAQ-DI) improvement >0.2 units and Clinical Disease Activity Index (CDAI) remission were compared at 1 year, imputing discontinued treatments as ‘non-response’. Additionally, we compared drug retention and changes in DAS28, HAQ-DI and CDAI from baseline to 3 months after treatment initiation. Results On average, baricitinib, and particularly tofacitinib, were initiated as later lines of therapy and more frequently as monotherapy compared with rituximab and TNFi. Adjusted 1 year response proportions were consistently lower on TNFi compared with baricitinib, with differences of −4.3 percentage points (95% CI −8.7, 0.1) for good EULAR response, −9.9 (−14.4 to −5.4) for HAQ-DI improvement and −6.0 (−9.8 to −2.2) for CDAI remission. Comparisons with non-TNFi bDMARDs also favoured baricitinib, but not consistently. Treatment responses for tofacitinib were only marginally lower than those for baricitinib and generally similar to those of bDMARDs, with precision limited by low power. Comparisons of drug retention and changes in disease activity from baseline to 3 months supported the 1 year findings. Conclusions Baricitinib and tofacitinib showed at least equivalent effectiveness compared with bDMARDs after exploring several different effectiveness measures.

Andrei Barbulescu,1 Viktor Oskarsson,2 Mats Lindblad,3,4 Rickard Ljung,1 Hannah L Brooke1 1Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; 2Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; 3Division of Surgery, Department of Clinical Science Intervention and Technology, Karolinska Institutet, Stockholm, Sweden; 4Centre for Digestive Diseases, Karolinska University Hospital, Stockholm, Sweden Objective: Oral metronidazole used in combined regimens for Helicobacter pylori eradication has been associated with an increased risk of acute pancreatitis; however, it is less clear whether a similar association exists for single-regimen metronidazole. We, therefore, examined the association of single and combined regimens of oral metronidazole with risk of acute pancreatitis.Methods: In this population-based case-control study, all individuals in Sweden (aged 40–84 years) hospitalized with acute pancreatitis between January 2006 and December 2008 were identified from a national hospital register (n=5,996). Controls, matched for calendar year, age, and sex, were randomly sampled from a national population register (n=60,681). Data on oral metronidazole and covariates were extracted from national health and prescription registers. Odds ratios (ORs) of acute pancreatitis, according to timing of the latest metronidazole prescription before hospitalization, were estimated using logistic regression models. Confounding by indication was examined by contrasting the main results with the association when amoxicillin was used as exposure. The robustness of results was examined by calculating incidence rate ratios using a self-controlled case series approach.Results: After adjustment for potential confounders, there was a substantially increased risk of acute pancreatitis within 30 days of oral metronidazole exposure, both for single (OR: 4.06; 95% confidence interval [CI]: 1.90–8.64) and combined (OR: 11.80; 95% CI: 6.86–20.28) regimens, compared to nonexposure. In contrast, the adjusted OR was 1.79 (95% CI: 1.25–2.54) for current use of amoxicillin compared to nonexposure. These results were supported by the self-controlled cases series analysis (incidence rate ratio: 3.30; 95% CI: 2.69–4.06, for single and combined regimens of oral metronidazole pooled). There was no strong association between oral metronidazole and acute pancreatitis more than 30 days after exposure.Conclusion: There was an increased risk of acute pancreatitis within 30 days of exposure to single and combined regimens of oral metronidazole. While reverse causality and confounding by indication cannot be entirely excluded, they are unlikely to fully explain the association. These results warrant an increased awareness among physicians. Keywords: case–control studies, Helicobacter infections, drug therapy, metronidazole, adverse effects, pancreatitis, epidemiology, Sweden

Background:The Janus kinase inhibitors (JAKi) have been increasingly used for the treatment of rheumatoid arthritis (RA) in Sweden, with baricitinib representing ~80% of prescriptions. Evidence regarding the comparative effectiveness of JAKis versus biologics (bDMARDs), and in particular non- tumour-necrosis-factor inhibitor (TNFi) bDMARDs, in real-life is limited.Objectives:To compare RA patients treated with bDMARDs and JAKi in Sweden, in terms of: (1) patient characteristics at treatment start; (2) proportions of patients remaining on therapy, and response rates, at 12 months.Methods:RA patients starting treatment in 2017 and 2018 with either a TNFi, rituximab, abatacept, interleukin 6 inhibitors (IL6i) or a JAKi as different lines of treatment were identified in the Swedish Rheumatology Quality Register. One patient could contribute with more than one treatment episode.Treatment response at 12 months was measured as EULAR good response, HAQ improvement >0.2 units, DAS28 and CDAI remission, and as 0 tender and swollen joint counts (28JC). Patients were classified as non-responders if they stopped treatment before evaluation due to safety or inefficacy. Responses for patients who stopped treatment due to pregnancy or death and patients on treatment but with missing response were imputed using multiple imputation.Proportions of responders and differences in proportions between treatment groups, adjusted using inverse probability of treatment weighting, were estimated using linear regression with robust standard errors.Results:JAKi were often used after bDMARDs, and less frequently prescribed in combination with methotrexate. Measured comorbidities were less frequent among JAKi initiators than among non-TNFi biologic initiators, but RA activity was similar (Table).Table 1.Patient characteristics at treatment initiationCharacteristicMedian (IQR) or N (%)AbataceptIL6iRituximabTNFiJAKiTreatment Starts6945346923497905Age63 (53-71)59 (48-70)65 (54-73)59 (47-68)60 (51-70)Female543 (78)441 (83)519 (75)2739 (78)759 (84)RA duration (years)13 (5-21)10 (5-18)12 (6-22)9 (3-17)13 (7-22)Rheum. factor535 (79)385 (73)588 (87)2405 (70)686 (77)DAS284.8 (3.9-5.6)4.9 (4.0-5.7)4.7 (3.8-5.5)4.4 (3.4-5.3)4.7 (3.9-5.7)HAQ1.3 (0.8-1.6)1.3 (0.8-1.8)1.3 (0.8-1.8)1.0 (0.5-1.4)1.3 (0.8-1.8)Tender joints5 (2-9)6 (3-10)5 (2-9)4 (2-8)6 (2-10)Swollen joints4 (2-6)4 (2-7)4 (2-7)3 (1-6)4 (2-7)ts/bDMARD line3 (2-4)3 (2-4)2 (1-4)1 (1-2)4 (2-6)At least one prev. TNFi539 (78)442 (83)457 (66)1448 (41)770 (85)At least one prev. non-TNFi271 (39)220 (41)243 (35)441 (13)584 (65)Methotrexate co-treatment264 (50)172 (40)286 (53)1708 (62)296 (40)Glucocorticoids co-treatment247 (47)186 (43)275 (51)1126 (41)389 (53)Cancer*90 (2.8)64 (2.3)363 (7.7)410 (1.8)20 (2.2)Cardio-vascular dis.*245 (7.5)123 (4.4)322 (6.8)749 (3.4)41 (4.4)Chronic respiratory dis.*303 (9.3)140 (5.0)473 (10.0)721 (3.2)50 (5.4)Diabetes*324 (9.9)216 (7.7)456 (9.7)1479 (6.7)69 (7.5)* any diagnosis within 5 years before start Adjusted differences in proportion with each response outcomeIn a crude comparison, 65% (61%-68%) of JAKi, 62% (59%-66%) of abatacept, 58% (53%-62%) of IL6i, 80% (77%-83%) of rituximab and 68% (67%-70%) of TNFi initiators remained on treatment at 12 months after start. Also, JAKi showed lower overall responder proportions than TNFi, rituximab and IL6i.After adjustment for demographic and socio-economic factors, RA disease activity, previous use of ts/bDMARDs, co-medication with glucocorticoids and methotrexate and comorbidities at baseline, no significant differences in responder proportions between JAKi and bDMARDs remained (Figure). Furthermore, the adjusted proportions of patients on treatment were higher for JAKi and rituximab than for the other bDMARDs.Conclusion:This preliminary analysis of patients treated in clinical practice found no statistically significant difference in effectiveness between JAKi and bDMARDs.Disclosure of Interests:Andrei Barbulescu: None declared, Johan Askling Grant/research support from: Abbvie, Astra-Zeneca, BMS, Eli Lilly, MSD, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB. These entities have entered into agreements with Karolinska Institutet with JA as principal investigator, mainly in the context of safety monitoring of biologics via the ARTIS national safety monitoring system, Katerina Chatzidionysiou Speakers bureau: Eli Lilly, Abbvie and Pfizer, Consultant of: Eli Lilly, Abbvie and Pfizer, Helena Forsblad-d’Elia: None declared, Alf Kastbom Employee of: Sanofi, Ulf Lindström: None declared, Carl Turesson Speakers bureau: Abbvie, Bristol-Myers Squibb, Medac, Pfizer, Roche, Consultant of: Roche, Grant/research support from: Bristol-Myers Squibb, Thomas Frisell: None declared

Background Use of glucocorticosteroids and NSAIDS for the treatment of RA has been associated with an increased risk of gastrointestinal (GI) perforations. The introduction of disease modifying agents, such as methotrexate or tumour necrosis factor inhibitors (TNFi) provided a seemingly safer treatment option, but the safety of other types of biologics relative to TNFi remains unclear. Objectives To estimate the incidence of gastro-intestinal perforations among Swedish RA patients treated with TNFi and non-TNFi biologics, and compare it with the incidence among bionaive patients with RA and a matched general population comparator group. Methods We performed a register-based cohort study, including all Swedish RA patients, with follow-up between 2010 and 2015. For these, all treatment initiations with biologic disease modifying anti-rheumatic drugs were identified through the Swedish Rheumatology register (SRQ), and grouped by class into TNFi and non-TNFi drugs (10 857 and 5823 treatment starts). Biologics naive patients with RA were identified by recorded diagnosis in the Swedish National Patient Register (NPR), since 2001 (n=54,732). Five general population controls were matched to each biologic-treated patient with RA (n=53,214) by sex, age, and geographical region. A patient could participate to several of these exposure cohorts. For each patient, follow-up under a cohort ended either with an outcome event (GI perforation identified in the NPR as an ICD10 code from a predefined list) or with the first of any of the following censoring events: emigration from Sweden, death, transition to another cohort, discontinuation of treatment (+90/+180 days lag time) or end of study period. Crude incidence rates were tabulated for each cohort and adjusted hazard ratios (HR) and 95% confidence intervals were estimated in multivariable Cox regressions, controlling for baseline differences. The final adjusted model included the following covariates: sex, age, line of biologic treatment, disease characteristics, co-medication at treatment start, co-morbidities and a history of GI perforation. Results We found 31 GI perforations among 18 604 person-years (pyr) exposed to TNFi, and 31 GI perforations among 10 947 pyr exposed to non-TNFi, corresponding to crude incidence rates of 1.67 and 2.83 per 1000 pyr, respectively. The crude incidence rate among the biologics-naive was 2.54 while among the general population comparators it was 0.94. The rate of GI perforations remained higher in patients with RA compared to the general population after adjustment for patient characteristics, HR of 1.78 (95% CI: 1.44 to 2.17), whereas the seemingly increased rate among bionaive and non-TNFi users vs TNFi was largely explained by differences in age and disease history at start of follow-up, with adjusted HRs of 1.10 (0.68–1.78) for TNFi vs bionaive and 1.10 (0.63–1.91) for TNFi vs non-TNFi, respectively. Conclusions Although patients with RA had a higher rate of GI perforations than matched general population comparators, no significant differences in risk remained between bionaive, TNFi or non-TNFi treated RA patients after adjusting for baseline patient characteristics. Disclosure of Interest None declared