Outcomes after anti-tumour necrosis factor originator to biosimilar switching in children and young people with juvenile idiopathic arthritis in the UK: a national cohort study.

BACKGROUND: For cost-saving purposes, children and young people with juvenile idiopathic arthritis (JIA) are being switched (for non-medical reasons) from biological originators to biosimilars. Here, we aimed to investigate those who switched from an anti-tumour necrosis factor (TNF) originator to a biosimilar, regarding drug survival and disease activity, compared with a matched cohort who continued the originator. METHODS: This analysis included all patients in the UK JIA Biologics Register switching directly from an anti-TNF originator to a biosimilar of the same product. All patients were matched (age, sex, disease duration, calendar year of when patients started originator therapy, line of therapy, and International League of Associations for Rheumatology [ILAR] category) to patients continuing the originator. For those matched successfully, a Cox proportional hazard model assessed whether drug persistence differed between those who switched compared with those who continued the originator. Overall change in the 71-joint juvenile arthritis disease activity score and the proportion of patients with a clinically important worsening score (by ≥1·7 units) after 6 months was compared between cohorts. This analysis was designed to address a priority research area set by our patient partners. FINDINGS: There were 224 children and young people with non-systemic JIA (139 [62%] were female, and 85 [38%] were male) identified as switching from a biological originator to a biosimilar of the same product from Jan 1, 2017, to July 7, 2023. 143 (64%) patients were originally on adalimumab, 56 (25%) on etanercept, and 25 (11%) on infliximab. Of these, 164 patients were matched successfully to those continuing the originator. There was no evidence that patients switching were more likely to stop treatment compared with those continuing the originator, with a hazard ratio of 1·46 (95% CI 0·93-2·30). Of the 51 patients in the biosimilar group who stopped treatment, 18 (35%) switched back to the originator (14 in the first year), 28 (55%) started a different biological drug, and five (10%) discontinued all treatment by the last follow-up. Of the 87 matched patients with available disease activity, there was no evidence that JADAS-71 worsened more after 6 months, with an odds ratio of 0·71 (95% CI 0·34-1·51; p=0·38). INTERPRETATION: In this matched comparative effectiveness analysis, children and young people with JIA switched from originators to biosimilars. Disease activity was similar between patients switching compared with those continuing the originator. Three quarters of patients were still receiving their biosimilar after 1 year, with switching back to originator uncommon, at only 9% after 1 year, suggesting good tolerability of non-medical switching in this patient population. This information is reassuring to clinicians and patients regarding the effect of non-medical biological switching. FUNDING: British Society for Rheumatology, Versus Arthritis, and National Institutes for Health Research Manchester Biomedical Research Centre.

Factors associated with disease flare following SARS-CoV-2 vaccination in people with inflammatory rheumatic and musculoskeletal diseases: results from the physician-reported EULAR Coronavirus Vaccine (COVAX) Registry.

OBJECTIVES: To investigate the frequency and factors associated with disease flare following vaccination against SARS-CoV-2 in people with inflammatory/autoimmune rheumatic and musculoskeletal diseases (I-RMDs). METHODS: Data from the European Alliance of Associations for Rheumatology Coronavirus Vaccine physician-reported registry were used. Factors associated with flare in patients with I-RMDs were investigated using multivariable logistic regression adjusted for demographic and clinical factors. RESULTS: The study included 7336 patients with I-RMD, with 272 of 7336 (3.7%) experiencing flares and 121 of 7336 (1.6%) experiencing flares requiring starting a new medication or increasing the dosage of an existing medication. Factors independently associated with increased odds of flare were: female sex (OR=1.40, 95% CI=1.05 to 1.87), active disease at the time of vaccination (low disease activity (LDA), OR=1.45, 95% CI=1.08 to 1.94; moderate/high disease activity (M/HDA), OR=1.37, 95% CI=0.97 to 1.95; vs remission), and cessation/reduction of antirheumatic medication before or after vaccination (OR=4.76, 95% CI=3.44 to 6.58); factors associated with decreased odds of flare were: higher age (OR=0.90, 95% CI=0.83 to 0.98), non-Pfizer/AstraZeneca/Moderna vaccines (OR=0.10, 95% CI=0.01 to 0.74; vs Pfizer), and exposure to methotrexate (OR=0.57, 95% CI=0.37 to 0.90), tumour necrosis factor inhibitors (OR=0.55, 95% CI=0.36 to 0.85) or rituximab (OR=0.27, 95% CI=0.11 to 0.66), versus no antirheumatic treatment. In a multivariable model using new medication or dosage increase due to flare as the dependent variable, only the following independent associations were observed: active disease (LDA, OR=1.47, 95% CI=0.94 to 2.29; M/HDA, OR=3.08, 95% CI=1.91 to 4.97; vs remission), cessation/reduction of antirheumatic medication before or after vaccination (OR=2.24, 95% CI=1.33 to 3.78), and exposure to methotrexate (OR=0.48, 95% CI=0.26 to 0.89) or rituximab (OR=0.10, 95% CI=0.01 to 0.77), versus no antirheumatic treatment. CONCLUSION: I-RMD flares following SARS-CoV-2 vaccination were uncommon. Factors associated with flares were identified, namely higher disease activity and cessation/reduction of antirheumatic medications before or after vaccination.

Factors facilitating and hindering South Asian immigrant adults from engaging in exercise and physical activity - a qualitative systematic review.

BACKGROUND: Exercise and physical activity are key components of management in patients with rheumatic musculoskeletal diseases (RMD), but people of the South Asian communities have a lower level of engagement with these activities compared to their Caucasian counterparts. The aim of this qualitative systematic review was to determine the barriers and facilitators of exercise and physical activity in South Asian communities who have migrated and live in western countries, particularly in those who have RMD. METHODS: Qualitative studies, published in English between 1999 and 2021 and including evaluation of barriers and/or facilitators to exercise or physical activity behaviour in people of South Asian adult communities who have migrated and/or lived in western countries were identified from Embase, MEDLINE, CINAHL, PsycINFO, Google Scholar and manual searches. The studies were appraised using the CASP checklist. Inductive thematic synthesis was used to identify common and global themes. RESULTS: A total of 32 studies that discussed barriers and facilitators of physical activity in South Asian communities who have migrated and lived in western countries were used for this review but there were no studies identified that focussed specifically on those with RMD. Following appraisal of the reporting of the studies, 30 studies were included in the pooling of the results. The facilitators and barriers to physical activities were broadly categorized into 'extrinsic' and 'intrinsic' factors. Extrinsic factors such as 'opportunity' included environmental factors such as weather and safety; socioeconomic factors such as education, language and literacy, and support in the form of social, psychological and resources. Intrinsic factors included cultural factors, such as life stages and family influence, beliefs and knowledge, which impacted attitudes and skills. CONCLUSIONS: This review has synthesised evidence of barriers or facilitators and identified potentially modifiable factors influencing physical activity and exercise engagement, which could form the basis of evidence-based interventions to promote participation in healthy behaviour change. Provision of a safe, comfortable and culturally acceptable environment together with culturally-aligned cognitive strategies to facilitate acquisition of exercise-efficacy skills could help engagement. REGISTRATION: The systematic review was registered on PROSPERO, registration no. 289,235.

Potential impact of European Medicines Agency measures to minimise risk of serious side effects on JAKi prescribing and utilisation in the UK.

OBJECTIVE: Janus kinase inhibitors (JAKi) or targeted synthetic (ts) disease-modifying antirheumatic drugs (DMARDs) effectively treat rheumatoid arthritis (RA). However, due to safety concerns, the European Medicines Agency (EMA) published risk minimisation measures limiting JAKi prescription to certain at-risk patients unless no suitable alternative is available. This analysis included patients who had started their first-ever JAKi before EMA measures were published in a large national cohort study to investigate the potential impact of these measures on JAKi prescribing and utilisation in UK. METHOD: RA patients starting first-ever JAK inhibitor therapy in BSRBR-RA between 13-February-2017 and 31-May-2022 were included. Percentages of patients meeting EMA risk criteria were presented. For at-risk patients, previous number of distinct biological (b) DMARD classes were described. RESULT: A total of 1341 patients were included, and 80% (N = 1075) met ≥1 EMA risk criterion. Of those who met ≥1 risk criterion, 529 patients (49%) had received JAKi as their first or second b/tsDMARD class, whereas 299 (28%) had received ≥3 prior bDMARD classes. CONCLUSION: Four-in-five RA patients commencing JAKi before the EMA advisory were considered 'at-risk' with prescribing only advised if there was no suitable alternative. Almost a third of those patients had already received ≥3 bDMARDs classes, and alternative therapies would be very limited for them; meanwhile, suitable alternatives might have existed for the remaining proportion, especially for those who received JAKi as their first or second b/tsDMARD, and re-evaluation of the suitability of their treatment may be needed.

Comparative Effectiveness of a Second Tumor Necrosis Factor Inhibitor Versus a Non-Tumor Necrosis Factor Biologic in the Treatment of Patients With Polyarticular-Course Juvenile Idiopathic Arthritis.

OBJECTIVE: The objective of this study was to compare the effectiveness of a second tumor necrosis factor inhibitor (TNFi) versus a non-TNFi biologic following discontinuation of a TNFi for patients with polyarticular-course juvenile idiopathic arthritis (pJIA). METHODS: Using the Childhood Arthritis and Rheumatology Research Alliance Registry, patients with pJIA who started receiving a second biologic following a first TNFi were identified. Patients were required to have no active uveitis on the index date and a visit six months after the index date. Outcome measures included Clinical Juvenile Arthritis Disease Activity Score with a maximum of 10 active joints (cJADAS10), cJADAS10 inactive disease (ID; ≤2.5) and cJADAS10 minimal disease activity (MiDA; ≤5). Multiple imputation was used to account for missing data. Adjusted odds ratios (aORs) were calculated using propensity score quintiles to compare outcomes at six months following second biologic initiation. RESULTS: There were 216 patients included, 84% initially received etanercept, and most patients stopped receiving it because of its ineffectiveness (74%). A total of 183 (85%) started receiving a second TNFi, and 33 (15%) started receiving a non-TNFi. Adalimumab was the most common second biologic received (71% overall, 84% of second TNFi), and tocilizumab was the most common non-TNFi second biologic received (9% overall, 58% of non-TNFi). There was no difference between receiving TNFi versus non-TNFi in cJADAS10 ID (29% vs 25%; aOR 1.23, 95% confidence interval [CI] 0.47-3.20) or at least MiDA (43% vs 39%; aOR 1.11, 95% CI 0.47-2.62) at six months. CONCLUSION: Most patients with pJIA started receiving TNFi rather than non-TNFi as their second biologic, and there were no differences in disease activity at six months.

Barriers and enablers to engagement in exercise and physical activity in non-English speaking South Asian people with chronic musculoskeletal disease.

BACKGROUND: Exercise and physical activity (EPA) are recommended for people with chronic musculoskeletal disease; however, lower levels of engagement with EPA has been consistently reported in people from the South Asian community across a range of diseases. As language can pose a significant barrier in healthcare, this study aimed to understand the enablers and barriers to the acceptance of EPA among non-English speaking South Asian people who attended rheumatology clinics. METHODS: 12 non-English speaking individuals from the South Asian community who had chronic musculoskeletal disease with significant pain scores were interviewed via telephone or face-to-face in their spoken languages. The audio recordings of the interviews were translated into English and transcribed verbatim. Data was analysed using thematic analysis implemented in the NVivo 12 Pro software program. RESULTS: The mean age was 52 years (9 women and 2 men). One main theme was identified: 'Enablers and barriers to exercise and physical activity'. Enablers to EPA were having knowledge about the benefits of EPA, being given resources in a language that they understood, and supportive environments such as having access to community facilities for those who could not undertake EPA in their houses. Barriers included physical health such as pain and fatigue, lack of time, difficulties with transportation to exercise venues, dislike of group exercises and lack of understanding of what and how to do exercise and be physically active. Participants' beliefs about EPA and whether they impacted their physical health seemed to influence whether they were undertaken or not. There was a perception that their culture shaped their compatriots' beliefs about EPA, and it was not normal practice for people from their country of birth to engage in it. CONCLUSIONS: This is the first qualitative study to explore the barriers and enablers to engagement in EPA in non-English speaking South Asian people with chronic musculoskeletal disease. Modifiable factors such as addressing the level of knowledge on the benefits of EPA in the management of chronic joint and muscle pain; aiding the development of the skills required to exercise safely and confidently despite chronic pain and providing information and services in the native language could promote the EPA engagement of non-English speaking South Asian individuals with chronic musculoskeletal disease. The findings may inform improvements within clinical services to promote the benefits, impact and self-efficacy of engagement with EPA as part of chronic musculoskeletal disease management. ETHICS APPROVAL: The West Midlands-Edgbaston Research Ethics Committee (reference:20/WM/0305).

Annals of the Rheumatic Diseases collection on pregnancy 2018-2023: observational data-driven knowledge.

Pregnancy can be an exciting time but for those living with rheumatic musculoskeletal diseases (RMDs), it can also be a time fraught with concern, including what effect pregnancy will have on the underlying RMD and what effect the RMD may have on the pregnancy and the baby, including the effects of medications. Generating an evidence base in pregnancy is challenging. Few interventional trials of medications in RMD pregnancies have ever been conducted, often for concerns of safety for both the mother and the child. Therefore, observational research remains important for informing clinical practice and helping women with RMDs make decisions regarding their health preconception and during pregnancy. The Annals of the Rheumatic Diseases (ARD) continues to publish important research on pregnancy in RMDs to increase the evidence base on this subject. Here we present an overview of papers published on this topic between January 2018 and December 2023. Our focus includes papers on pregnancy and RMD outcome, the effects of drug exposure, fetal outcomes as well as fertility.

Towards stratified treatment of JIA: machine learning identifies subtypes in response to methotrexate from four UK cohorts.

BACKGROUND: Methotrexate (MTX) is the gold-standard first-line disease-modifying anti-rheumatic drug for juvenile idiopathic arthritis (JIA), despite only being either effective or tolerated in half of children and young people (CYP). To facilitate stratified treatment of early JIA, novel methods in machine learning were used to i) identify clusters with distinct disease patterns following MTX initiation; ii) predict cluster membership; and iii) compare clusters to existing treatment response measures. METHODS: Discovery and verification cohorts included CYP who first initiated MTX before January 2018 in one of four UK multicentre prospective cohorts of JIA within the CLUSTER consortium. JADAS components (active joint count, physician (PGA) and parental (PGE) global assessments, ESR) were recorded at MTX start and over the following year. Clusters of MTX 'response' were uncovered using multivariate group-based trajectory modelling separately in discovery and verification cohorts. Clusters were compared descriptively to ACR Pedi 30/90 scores, and multivariate logistic regression models predicted cluster-group assignment. FINDINGS: The discovery cohorts included 657 CYP and verification cohorts 1241 CYP. Six clusters were identified: Fast improvers (11%), Slow Improvers (16%), Improve-Relapse (7%), Persistent Disease (44%), Persistent PGA (8%) and Persistent PGE (13%), the latter two characterised by improvement in all features except one. Factors associated with clusters included ethnicity, ILAR category, age, PGE, and ESR scores at MTX start, with predictive model area under the curve values of 0.65-0.71. Singular ACR Pedi 30/90 scores at 6 and 12 months could not capture speeds of improvement, relapsing courses or diverging disease patterns. INTERPRETATION: Six distinct patterns following initiation of MTX have been identified using methods in artificial intelligence. These clusters demonstrate the limitations in traditional yes/no treatment response assessment (e.g., ACRPedi30) and can form the basis of a stratified medicine programme in early JIA. FUNDING: Medical Research Council, Versus Arthritis, Great Ormond Street Hospital Children's Charity, Olivia's Vision, and the National Institute for Health Research.

Therapeutic advances in rheumatoid arthritis.

Rheumatoid arthritis (RA) is one of the most common immune mediated inflammatory diseases. People with rheumatoid arthritis present with pain, swelling, and stiffness that typically affects symmetrically distributed small and large joints. Without effective treatment, significant joint damage, disability, and work loss develop, owing to chronic inflammation of the joint lining (synovium). Over the past 25 years, the management of this condition has been revolutionized, resulting in substantially higher levels of disease remission and better long term outcomes. This improvement reflects a paradigm shift towards early and aggressive pharmacological intervention coupled with a proliferation in treatment choice, in turn related to enhanced pathobiological understanding and the advent of new drugs for rheumatoid arthritis. Following an overview of these developments from a historical perspective, and with a general audience in mind, this review focuses on newer, targeted treatments in an ever evolving landscape. The review highlights ongoing areas of debate and unmet need, including the proportion of patients with persistent, difficult-to-treat disease, despite recent advances. Also discussed are personalized, strategic approaches to individual patients, the role for imaging in clinical decision making, and the goal of sustained, drug free remission and disease prevention in the future.

Overlap of International League of Associations for Rheumatology and Preliminary Pediatric Rheumatology International Trials Organization Classification Criteria for Nonsystemic Juvenile Idiopathic Arthritis in an Established UK Multicentre Inception Cohort.

OBJECTIVE: The goal was to assess the degree of overlap between existing International League of Associations for Rheumatology (ILAR) and preliminary Paediatric Rheumatology International Trials Organisation (PRINTO) classification criteria for juvenile idiopathic arthritis (JIA). METHODS: Participants from the Childhood Arthritis Prospective Study, a multicenter UK JIA inception cohort, were classified using the PRINTO and ILAR classification criteria into distinct categories. Systemic JIA was excluded because several classification items were not collected in this cohort. Adaptations to PRINTO criteria were required to apply to a UK health care setting, including limiting the number of blood biomarker tests required. The overlap between categories under the two systems was determined, and any differences in characteristics between groups were described. RESULTS: A total of 1,223 children and young people with a physician's diagnosis of JIA were included. Using PRINTO criteria, the majority of the patients had "other JIA" (69.5%). There was a high degree of overlap (91%) between the PRINTO enthesitis/spondylitis- and ILAR enthesitis-related JIA categories. The PRINTO rheumatoid factor (RF)-positive category was composed of 48% ILAR RF-positive polyarthritis and 52% undifferentiated JIA. The early-onset antinuclear antibodies-positive PRINTO category was largely composed of ILAR oligoarthritis (50%), RF-negative polyarthritis (24%), and undifferentiated JIA (23%). A few patients were unclassified under PRINTO (n = 3) and would previously have been classified as enthesitis-related JIA (n = 1) and undifferentiated JIA (n = 2) under ILAR. CONCLUSION: Under the preliminary PRINTO classification criteria for childhood arthritis, most children are not yet classified into a named category. These data can help support further delineation of the PRINTO criteria to ensure homogenous groups of children can be identified.

Impact of Risk Factors on COVID-19 Outcomes in Unvaccinated People With Rheumatic Diseases: A Comparative Analysis of Pandemic Epochs Using the COVID-19 Global Rheumatology Alliance Registry.

OBJECTIVE: Approximately one third of individuals worldwide have not received a COVID-19 vaccine. Although studies have investigated risk factors linked to severe COVID-19 among unvaccinated people with rheumatic diseases (RDs), we know less about whether these factors changed as the pandemic progressed. We aimed to identify risk factors associated with severe COVID-19 in unvaccinated individuals in different pandemic epochs corresponding to major variants of concern. METHODS: Patients with RDs and COVID-19 were entered into the COVID-19 Global Rheumatology Alliance Registry between March 2020 and June 2022. An ordinal logistic regression model (not hospitalized, hospitalized, and death) was used with date of COVID-19 diagnosis, age, sex, race and/or ethnicity, comorbidities, RD activity, medications, and the human development index (HDI) as covariates. The main analysis included all unvaccinated patients across COVID-19 pandemic epochs; subanalyses stratified patients according to RD types. RESULTS: Among 19,256 unvaccinated people with RDs and COVID-19, those who were older, male, had more comorbidities, used glucocorticoids, had higher disease activity, or lived in lower HDI regions had worse outcomes across epochs. For those with rheumatoid arthritis, sulfasalazine and B-cell-depleting therapy were associated with worse outcomes, and tumor necrosis factor inhibitors were associated with improved outcomes. In those with connective tissue disease or vasculitis, B-cell-depleting therapy was associated with worse outcomes. CONCLUSION: Risk factors for severe COVID-19 outcomes were similar throughout pandemic epochs in unvaccinated people with RDs. Ongoing efforts, including vaccination, are needed to reduce COVID-19 severity in this population, particularly in those with medical and social vulnerabilities identified in this study.

A proteomics study of rheumatoid arthritis patients on etanercept identifies putative biomarkers associated with clinical outcome measures.

OBJECTIVES: Biologic DMARDs (bDMARDs) are widely used in patients with RA, but response to bDMARDs is heterogeneous. The objective of this work was to identify pretreatment proteomic biomarkers associated with RA clinical outcome measures in patients starting bDMARDs. METHODS: Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH-MS) was used to generate spectral maps of sera from patients with RA before and after 3 months of treatment with the bDMARD etanercept. Protein levels were regressed against RA clinical outcome measures, i.e. 28-joint DAS (DAS28) and its subcomponents and DAS28 <2.6 (i.e. remission). The proteins with the strongest evidence for association were analysed in an independent, replication dataset. Finally, subnetwork analysis was carried out using the Disease Module Detection algorithm and biological plausibility of identified proteins was assessed by enrichment analysis. RESULTS: A total of 180 patients with RA were included in the discovery dataset and 58 in the validation dataset from a UK-based prospective multicentre study. Ten individual proteins were found to be significantly associated with RA clinical outcome measures. The association of T-complex protein 1 subunit η with DAS28 remission was replicated in an independent cohort. Subnetwork analysis of the 10 proteins from the regression analysis identified the ontological theme, with the strongest associations being with acute phase and acute inflammatory responses. CONCLUSION: This longitudinal study of 180 patients with RA commencing etanercept has identified several putative protein biomarkers of treatment response to this drug, one of which was replicated in an independent cohort.

Socioeconomic deprivation is associated with reduced response and lower treatment persistence with TNF inhibitors in rheumatoid arthritis.

OBJECTIVE: To investigate the association between socioeconomic deprivation and outcomes following TNF inhibitor (TNFi) treatment. METHODS: Individuals commencing their first TNFi in the British Society for Rheumatology Biologics Register for RA (BSRBR-RA) and Biologics in RA Genetics and Genomics Study Syndicate (BRAGGSS) cohort were included. Socioeconomic deprivation was proxied using the Index of Multiple Deprivation and categorized as 20% most deprived, middle 40% or 40% least deprived. DAS28-derived outcomes at 6 months (BSRBR-RA) and 3 months (BRAGGSS) were compared using regression models with the least deprived as referent. Risks of all-cause and cause-specific drug discontinuation were compared using Cox models in the BSRBR-RA. Additional analyses adjusted for lifestyle factors (e.g. smoking, BMI) as potential mediators. RESULTS: 16 085 individuals in the BSRBR-RA were included (mean age 56 years, 76% female), of whom 18%, 41% and 41% were in the most, middle and least deprived groups, respectively. Of 3459 included in BRAGGSS (mean age 57, 77% female), proportions were 22%, 36% and 41%, respectively. The most deprived group had 0.3-unit higher 6-month DAS28 (95% CI 0.22, 0.37) and were less likely to achieve low disease activity (odds ratio [OR] 0.76; 95% CI 0.68, 0.84) in unadjusted models. Results were similar for 3-month DAS28 (ß = 0.23; 95% CI 0.11, 0.36) and low disease activity (OR 0.77; 95% CI 0.63, 0.94). The most deprived were more likely to discontinue treatment (hazard ratio 1.18; 95% CI 1.12, 1.25), driven by ineffectiveness rather than adverse events. Adjusted estimates were generally attenuated. CONCLUSION: Socioeconomic deprivation is associated with reduced response to TNFi. Improvements in determinants of health other than lifestyle factors are needed to address socioeconomic inequities.

Developing and externally validating multinomial prediction models for methotrexate treatment outcomes in patients with rheumatoid arthritis: results from an international collaboration.

OBJECTIVES: In rheumatology, there is a clinical need to identify patients at high risk (>50%) of not responding to the first-line therapy methotrexate (MTX) due to lack of disease control or discontinuation due to adverse events (AEs). Despite this need, previous prediction models in this context are at high risk of bias and ignore AEs. Our objectives were to (i) develop a multinomial model for outcomes of low disease activity and discontinuing due to AEs 6 months after starting MTX, (ii) update prognosis 3-month following treatment initiation, and (iii) externally validate these models. STUDY DESIGN AND SETTING: A multinomial model for low disease activity (submodel 1) and discontinuing due to AEs (submodel 2) was developed using data from the UK Rheumatoid Arthritis Medication Study, updated using landmarking analysis, internally validated using bootstrapping, and externally validated in the Norwegian Disease-Modifying Antirheumatic Drug register. Performance was assessed using calibration (calibration-slope and calibration-in-the-large), and discrimination (concordance-statistic and polytomous discriminatory index). RESULTS: The internally validated model showed good calibration in the development setting with a calibration-slope of 1.01 (0.87, 1.14) (submodel 1) and 0.83 (0.30, 1.34) (submodel 2), and moderate discrimination with a c-statistic of 0.72 (0.69, 0.74) and 0.53 (0.48, 0.59), respectively. Predictive performance decreased after external validation (calibration-slope 0.78 (0.64, 0.93) (submodel 1) and 0.86 (0.34, 1.38) (submodel 2)), which may be due to differences in disease-specific characteristics and outcome prevalence. CONCLUSION: We addressed previously identified methodological limitations of prediction models for outcomes of MTX therapy. The multinomial approach predicted outcomes of disease activity more accurately than AEs, which should be addressed in future work to aid implementation into clinical practice.

Evaluation of discontinuation for adverse events of JAK inhibitors and bDMARDs in an international collaboration of rheumatoid arthritis registers (the 'JAK-pot' study).

BACKGROUND: In a clinical trial setting, patients with rheumatoid arthritis (RA) taking the Janus kinase inhibitor (JAKi) tofacitinib demonstrated higher adverse events rates compared with those taking the tumour necrosis factor inhibitors (TNFi) adalimumab or etanercept. OBJECTIVE: Compare treatment discontinuations for adverse events (AEs) among second-line therapies in an international real-world RA population. METHODS: Patients initiating JAKi, TNFi or a biological with another mode of action (OMA) from 17 registers participating in the 'JAK-pot' collaboration were included. The primary outcome was the rate of treatment discontinuation due to AEs. We used unadjusted and adjusted cause-specific Cox proportional hazard models to compare treatment discontinuations for AEs among treatment groups by class, but also evaluating separately the specific type of JAKi. RESULTS: Of the 46 913 treatment courses included, 12 523 were JAKi (43% baricitinib, 40% tofacitinib, 15% upadacitinib, 2% filgotinib), 23 391 TNFi and 10 999 OMA. The adjusted cause-specific hazard rate of treatment discontinuation for AEs was similar for TNFi versus JAKi (1.00, 95% CI 0.92 to 1.10) and higher for OMA versus JAKi (1.11, 95% CI 1.01 to 1.23), lower with TNFi compared with tofacitinib (0.81, 95% CI 0.71 to 0.90), but higher for TNFi versus baricitinib (1.15, 95% CI 1.01 to 1.30) and lower for TNFi versus JAKi in patients 65 or older with at least one cardiovascular risk factor (0.79, 95% CI 0.65 to 0.97). CONCLUSION: While JAKi overall were not associated with more treatment discontinuations for AEs, subgroup analyses suggest varying patterns with specific JAKi, such as tofacitinib, compared with TNFi. However, these observations should be interpreted cautiously, given the observational study design.

The incidence and prevalence of Juvenile Idiopathic Arthritis differs between ethnic groups in England.

OBJECTIVES: Juvenile Idiopathic Arthritis (JIA) is a heterogenous group of rare autoimmune disorders characterised by chronic joint inflammation of unknown aetiology with onset under 16years. Accurate estimates of disease rates help understand impacts on individuals and society, and provide evidence for health service planning and delivery. This study aimed to produce the first national estimates of incidence and prevalence by ethnic group using electronic health records. METHODS: Data from the Clinical Practice Research Datalink (CPRD) Aurum, a primary care electronic health record database in England, were used to estimate the incidence and prevalence of JIA by ethnic group amongst children and young people aged under 16 years between 2003 and 2018, with cases validated using Hospital Episode Statistics (HES). Chi square was used to test the difference in proportions compared to the ethnic distribution of England. RESULTS: A total of 424 incident cases of JIA were identified, 389 validated using HES records. Incidence of JIA was higher amongst those of White ethnic group (6.2 per 100,000 population) compared to Mixed (3.0 per 100,000), Asian (2.7 per 100,000) and Black (2.9 per 100,000) communities. The ethnic group distribution of cases differed significantly compared to the general population (p < 0.0001). CONCLUSION: Incidence and prevalence of JIA differs between ethnic groups, and is different from the population. This is likely to be due to a combination of genetic and equity factors. Further research to understand the underlying cause of these differences is important, to enable targeted interventions and appropriate service provision.

The epidemiology of psoriatic arthritis in the UK: a health intelligence analysis of UK Primary Care Electronic Health Records 1991-2020.

OBJECTIVES: Epidemiological estimates of psoriatic arthritis (PsA) underpin the provision of healthcare, research, and the work of government, charities and patient organizations. Methodological problems impacting prior estimates include small sample sizes, incomplete case ascertainment, and representativeness. We developed a statistical modelling strategy to provide contemporary prevalence and incidence estimates of PsA from 1991 to 2020 in the UK. METHODS: Data from Clinical Practice Research Datalink (CPRD) were used to identify cases of PsA between 1st January 1991 and 31st December 2020. To optimize ascertainment, we identified cases of Definite PsA (≥1 Read code for PsA) and Probable PsA (satisfied a bespoke algorithm). Standardized annual rates were calculated using Bayesian multilevel regression with post-stratification to account for systematic differences between CPRD data and the UK population, based on age, sex, socioeconomic status and region of residence. RESULTS: A total of 26293 recorded PsA cases (all definitions) were identified within the study window (77.9% Definite PsA). Between 1991 and 2020 the standardized prevalence of PsA increased twelve-fold from 0.03 to 0.37. The standardized incidence of PsA per 100,000 person years increased from 8.97 in 1991 to 15.08 in 2020, an almost 2-fold increase. Over time, rates were similar between the sexes, and across socioeconomic status. Rates were strongly associated with age, and consistently highest in Northern Ireland. CONCLUSION: The prevalence and incidence of PsA recorded in primary care has increased over the last three decades. The modelling strategy presented can be used to provide contemporary prevalence estimates for musculoskeletal disease using routinely collected primary care data.

Outcomes following switching from etanercept originator to etanercept biosimilar in 1024 RA patients: A matched-analysis of the BSRBR-RA.

OBJECTIVES: Adults with RA are being switched from etanercept originator to biosimilar in non-medical/cost-saving switching. This analysis aims to investigate outcomes in these patients, including (a) drug survival and (b) disease activity at six and 12-month, compared with those who remain on originator. METHODS: Using BSRBR-RA, those who switched directly from etanercept originator to biosimilar were identified and matched to patients receiving originator, based on gender, age, disease duration, originator start year. Drug survival was calculated; Cox-proportional hazard models assessed differences in drug persistence between those who switched versus remaining on originator. Change in DAS28 after six and 12-months was compared between cohorts. Multiple imputation was used. RESULTS: 1024 adults with RA switching from etanercept originator to biosimilar were included, with a matched cohort of patients remaining on originator. Patients who switched onto a biosimilar product were no more likely to discontinue etanercept treatment versus those who remained on originator; hazard ratio 1.06 (95%CI 0.89-1.26), with 65% of patients remaining on treatment at three years. Ninety-five (9%) patients switched back to originator within the first year. After six and 12-months, biosimilar patients were no more likely to have a worsening of DAS28 (>0.6units) compared with those who remained on originator. CONCLUSIONS: This is the largest matched comparative effectiveness analysis showing patients switched from etanercept originator to biosimilar appear to do just as well with regards to disease activity and drug persistence compared with those who remained on originator. These data will be reassuring to clinicians and patients regarding non-medical switching.