Background and Importance There is evidence on the influence of sex on the effectiveness and safety of drugs, as pharmacokinetics and pharmacodynamics differ between women and men. Women exhibit higher blood drug concentrations and longer drug clearance times compared to men. To date, there is limited real-world data assessing the influence of sex on the effectiveness of Janus kinase inhibitors (JAKi) in rheumatoid arthritis (RA) treatment.

Aim and Objectives (a) To compare the probability of reaching remission in women and men treated with JAKi, and (b) to analyse the potential impact of sex on JAKi treatment discontinuation due to lack of effectiveness.

Material and Methods This observational retrospective study involved the RA patients who were treated with tofacitinib, baricitinib, upadacitinib, or filgotinib at a tertiary hospital, between September 2017 and September 2023.

Logistic regression was applied to compare the odds of reaching remission (defined by the Disease Activity Score 28-joints using Erythrocyte Sedimentation Rate [DAS28-ESR] of <2.6) at 6 months in women versus men. The Cox model was used to analyse sex as a potential predictive factor that could influence JAKi treatment discontinuation due to lack of effectiveness. Statistical analyses were performed utilising STATA software.

Results 184 JAKi treatments were included, corresponding to 123 RA patients (86% women, 63±13 years old).

There were no significant differences in baseline RA disease activities between women (DAS28-ESR: 5.0 [SD 1.3]) and men (DAS28-ESR: 4.7 [SD 1.3]), p=0.251. At 6 months of JAKi treatment, women were more likely to reach DAS28-ESR remission in comparison with men (odds ratio [OR]: 2.72, 95%CI: 1.05–7.10; p=0.040). Discontinuation rates of JAKi treatment due to lack of effectiveness were not related with sex (hazard ratio [HR]: 1.14, 95%CI: 0.54–2.41; p=0.732).

Conclusion and Relevance Women with RA who received treatment with JAKi possessed higher odds of reaching remission at 6 months of treatment than men. Sex was not found to impact on JAKi treatment discontinuation due to lack of effectiveness.

Conflict of Interest No conflict of interest.