Real-world experience with Janus kinase inhibitors in rheumatoid and psoriatic arthritis: retention and discontinuation factors in a UK six-centre cohort

Abstract Objectives To investigate real-world use of Janus kinase inhibitors (JAKi) prescribed for rheumatoid and psoriatic arthritis (RA, PsA). Methods We conducted a retrospective review of all patients treated with Baricitinib, Filgotinib, Tofacitinib and Upadacitinib across six UK rheumatology centres from time of first use in routine care until November 2024. Standardised data was collected, and retention was calculated using Kaplan-Meier analysis. Factors associated with JAKi discontinuation were analysed using multivariable Cox regression analyses. Results A total of 985 patients (79.5% female, mean age 60 years, RA 849 [86.2%], PsA 136 [13.8%]) were reviewed. Methotrexate and glucocorticoids were co-prescribed in 43% and 33.6% of cases. Among glucocorticoid users, dose reduction occurred in 18% and complete discontinuation in 61.8%. JAKi were prescribed as first-line biologic-DMARD in 7.5% and as third-line or later in 78.8%. Median retention was 49 months (range 1–85, 95%CI = 42.62–55.37), with 52.8% remaining on treatment at censure, with no difference between RA and PsA populations. Retention on Tofacitinib was significantly lower than Baricitinib (p < 0.001) and Upadacitinib (p = 0.007). Variables significantly associated with higher JAKi discontinuation risk were female sex (HR = 1.66; 95%CI = 1.28–2.16), increasing age (HR = 1.01; 95%CI = 1.00–1.02) and Tofacitinib (versuss Baricitinib) treatment (HR = 2.27; 95%CI = 1.64–3.14). Among RA patients, methotrexate co-prescription was associated with a lower discontinuation risk (HR = 0.81; 0.66–0.98). Conclusion In a real-world setting, JAKi demonstrated high retention in RA and PsA, with a glucocorticoid-sparing effect. Retention is lower for female sex, older age, Tofacitinib versuss Baricitinib, and use without MTX in RA, whereas place in treatment pathway did not impact retention outcomes.