Risk of Spondyloarthritis in Patients With Inflammatory Bowel Disease Receiving Treatment With Biologics or Janus Kinase Inhibitors.

Objective: To detect spondyloarthritis (SpA) and evaluate risk factors in patients with inflammatory bowel disease (IBD) during biologic or Janus kinase inhibitor (JAKi) treatment.

Methods: This was a retrospective cohort study of patients with IBD receiving biologics or JAKi, excluding prior SpA cases. We identified patients who developed musculoskeletal (MSK) symptoms during IBD treatment. SpA was diagnosed after a clinical evaluation by a rheumatologist alongside imaging analysis of conventional radiographs and HLA-B27 determination. Magnetic resonance imaging of the sacroiliac joints was performed only in cases where the conventional radiograph was inconclusive.

Results: Of 1649 patients with IBD receiving biologic or JAKi treatment (Crohn disease: 1335; ulcerative colitis [UC]: 314), 96 (5.8%) were excluded due to a prior SpA diagnosis. Among the remaining 1553 patients, 106 (6.8%) developed MSK symptoms during IBD treatment, and 30 (1.9%) were diagnosed with SpA (axial: 20; peripheral: 10) during the follow-up (median 5.2 [IQR 3.4-7.5] years). Risk factors for SpA in these patients included a partial Mayo score for UC at the time of onset of MSK symptoms (hazard ratio [HR] 1.57; P = 0.03) and HLA-B27 positivity (HR 3.70; P = 0.004). As well as IBD treatment, 23/30 (77%) patients with SpA used nonsteroidal antiinflammatory drugs (NSAIDs). IBD disease activity did not worsen during treatment, regardless of NSAID use.

Conclusion: During a median follow-up of 5.2 years, 6.8% of patients with IBD undergoing biologic or JAKi treatment developed MSK symptoms, with one-third subsequently diagnosed with SpA. HLA-B27 positivity and higher UC disease activity were associated with an increased risk of SpA.