Background and importance Janus kinases (JAK) inhibitors, baricitinib and tofacitinib, have emerged as an effective class in the treatment of rheumatoid arthritis (RA), which when administered orally offer an alternative to subcutaneous or intravenous biologic drugs, with efficacy and safety results comparable with those of biological therapies.

Aim and objectives To assess the effectiveness, safety and adherence to JAK inhibitors in patients with RA.

Material and methods A retrospective observational study was conducted in patients diagnosed with RA who received treatment with JAK inhibitors between 2017 and 2019 in a secondary hospital. Variables included were: sex, age, time since diagnosis, number of previous biologic treatments, dose and concomitant use of conventional disease modifying antirheumatic drugs. Clinical disease activity was assessed at months 0, 6 and 12 using the DAS28-ESR score.

Safety was evaluated according to adverse effects (AE). Adherence was calculated using the medication possession ratio (MPR), percentage of days’ supply obtained/refill interval or fixed interval, obtained from the pharmacy system.

Results 36 patients were included, 86% women (4 patients received both treatments). Age was 54 (SD 9) years and average time since diagnosis was 11 (SD 7) years. Average number of previous biologics was 2 (IQR 0–4). Treatment prescriptions were 50% tofacitinib (5 mg twice daily) and 50% baricitinib (4 mg four times a day except for two patients who had 2 mg four times a day). 53% of patients were taking concomitant methotrexate and 8% leflunomide.

From the 40 treatments assessed, 12 were stopped before 6 months and 3 before 12 months. The main reasons for discontinuation were: AE (40%) (headache, meningitis, oedema, skin lesions), primary treatment failure (33%) and secondary treatment failure (20%). DAS28-ESR before JAK inhibitors was 4.9 (SD 0.7), at 6 months 3.4 (SD 1.1) (22% in remission) and 3.4 (SD 0.5) (0% in remission) at 12 months. DAS28-ESR was reduced by ≥1.2 points (moderate response) in 44% of patients at 12 months.

AE were observed in 44% of patients, most commonly: infections (14%), headache (11%) and gastrointestinal disorders (8%). The mean MPR was 92 (SD 0.1)% after 6 and 12 months. Two patients had an MPR < 80% at 6 months and 4 at 12 months.

Conclusion and relevance In our study, the percentage of adherence to JAK inhibitors was high. Despite no patients in remission at 12 months, almost half showed a moderate response to treatment. However, more than a third of patients reported AE.

Conflict of interest No conflict of interest