Prevalence of and factors associated with radiographic sacroiliitis in Japanese patients with inflammatory bowel disease: a computed tomography–based study

Abstract Objective To determine the prevalence of radiographic sacroiliitis—a classification feature of spondyloarthritis—and to identify associated factors in Japanese patients with inflammatory bowel disease. Methods This retrospective study included 880 patients with ulcerative colitis or Crohn’s disease who underwent abdominopelvic computed tomography at an inflammatory bowel disease centre. Sacroiliac joints were evaluated using a validated scoring system. Radiographic sacroiliitis was defined as a total erosion score ≥3 or the presence of sacroiliac joint ankylosis. Multivariate logistic regression analysis identified factors associated with radiographic sacroiliitis. Results Radiographic sacroiliitis was identified in 98 patients (11%), including 41 patients (5%) with complete ankylosis. Crohn’s disease (vs. ulcerative colitis; odds ratio [OR] 2.14; 95% confidence interval [CI], 1.17–3.89), male sex (OR 3.85; 95% CI 1.96–7.56), and older age (OR 1.07 per year; 95% CI 1.05–1.09) were independently associated with radiographic sacroiliitis. In subgroup analysis, obesity was associated with radiographic sacroiliitis in Crohn’s disease (OR 2.15; 95% CI 1.01–4.59). Conclusions Radiographic sacroiliitis was present in approximately 10% of Japanese patients with inflammatory bowel disease. Evaluation of sacroiliac joints on routine abdominopelvic computed tomography may help identify patients warranting further evaluation for coexisting spondyloarthritis, particularly in older men with Crohn’s disease.