Clinical Characteristics and 1-Year Response in Rheumatic Mexican Patients Using JAK Inhibitors: Data From BIOBADAMEX.

Objective: We aim to evaluate the clinical features, first-year treatment response, and frequency of adverse events in Mexican patients receiving Janus kinase inhibitor (JAK-i) using data from the Mexican Adverse Events Registry (BIOBADAMEX).

Methods: We included all BIOBADAMEX patients from 2022 to 2024 and described the sociodemographic, clinical, treatment characteristics and adverse events of the approved JAK-i in Mexico: tofacitinib, baricitinib, and upadacitinib. We assessed the JAK-i efficacy comparing baseline and the 1-year response mean disease activity scores.

Results: A total of 222 patients were included, 39.6% received tofacitinib, 47.3% baricitinib, and 13.1% upadacitinib. The most common diagnosis was rheumatoid arthritis (77%). Sixty-eight percent of patients had comorbidities, 6% had prior history of malignancy, and 57% previously used a biologic. Mean age at JAK-i initiation was 49.6 (±13.9) years with an overall latency period of 9.4 years. DAS28 (Disease Activity Score in 28 joints) reduced from 4.7 (±1.2) at baseline to 2.99 (±1.2) in the first year (p = 0.001), and Bath Ankylosing Spondylitis Disease Activity Index from 4.8 (±3.9) to 2 (±1.5). JAK-i withdrawal was 29%; nonmedical reasons were the main motive. Sixty-five adverse events were reported; all were nonsevere with only 1 case of herpes zoster and no reports of malignancy or thrombosis. Differences in clinical and treatment characteristics between JAK-i were found.

Conclusions: Our study showed older age for JAK-i initiation, a lower overall latency period, and lower use of prior biologic disease-modifying antirheumatic drug when compared with existing data in the literature. The main motive for JAK-i withdrawal was nonmedical reasons. Adverse events were nonsevere; interestingly, there was only 1 case of herpes zoster and no reports of malignancy or thrombosis.