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

## TL;DR

This study examines how Janus kinase inhibitors are used in real-world treatment of rheumatoid and psoriatic arthritis in the UK, focusing on patient retention and reasons for discontinuation.

## Contribution

The study provides real-world evidence on JAKi retention and discontinuation factors in rheumatoid and psoriatic arthritis patients.

## Key findings

- Median JAKi retention was 49 months with no difference between rheumatoid arthritis and psoriatic arthritis patients.
- Tofacitinib had lower retention compared to baricitinib and upadacitinib.
- Female sex, older age, and lack of methotrexate co-prescription were associated with higher discontinuation risk.

## Abstract

To investigate real-world use of Janus kinase inhibitors (JAKis) prescribed for RA and PsA.

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 were collected and retention was calculated using Kaplan–Meier analysis. Factors associated with JAKi discontinuation were analysed using multivariable Cox regression analyses.

A total of 985 patients [79.5% female, mean age 60 years, RA 849 (86.2%), PsA 136 (13.8%)] were reviewed. MTX and glucocorticoids (GCs) were co-prescribed in 43% and 33.6% of cases, respectively. Among GC users, dose reduction occurred in 18% and complete discontinuation in 61.8%. JAKis were prescribed as a first-line biologic DMARD in 7.5% and as a 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 [hazard ratio (HR) 1.66 (95% CI 1.28, 2.16)], increasing age [HR 1.01 (95% CI 1.00, 1.02)] and tofacitinib (vs baricitinib) treatment [HR 2.27 (95% CI 1.64, 3.14)]. Among RA patients, MTX co-prescription was associated with a lower discontinuation risk [HR 0.81 (95% CI 0.66, 0.98)].

In a real-world setting, JAKi demonstrated high retention in RA and PsA, with a GC-sparing effect. Retention is lower for female sex, older age, tofacitinib vs baricitinib and use without MTX in RA, whereas place in the treatment pathway did not impact retention outcomes.