816 The Prevalence and Clinical Associations of Sacroiliitis in Crohn’s Disease Using a Standardized Magnetic Resonance Scoring System

Abstract

INTRODUCTION: Sacroiliitis (SI), an inflammatory arthropathy of the sacroiliac joints, has an established correlation with Inflammatory Bowel Disease (IBD). Yet SI often goes undiagnosed, and the clinical association between IBD disease activity and SI is not established. Patients with Crohn’s disease (CD) often receive magnetic resonance enterography (MRE), affording clinicians the opportunity to evaluate for the presence of sacroiliitis. We sought to identify the prevalence and disease characteristics associated with SI in CD using MRE. METHODS: All CD patients undergoing MRE for any reason between 2014-2018 at an IBD referral center were identified. A musculoskeletal radiologist reviewed all MRE exams for acute and chronic SI using standardized scoring. We analyzed demographics, IBD characteristics, clinical and endoscopic activity, and management between CD patients with and without SI. RESULTS: 258 patients with CD underwent MRE during the study period. The mean age was 35 years old, 53% were male, and mean duration of CD at MRE was 9 years. Few reported back pain (8%) and 14% had previously seen a rheumatologist. Overall, 17% (n = 45) of patients had MR evidence of SI (Table 1). Female gender, back pain, and later age of CD diagnosis were associated with SI (P = 0.05, P < 0.001; P = 0.04 respectively; Table 2). Disease location and medication exposures were not associated with SI. Stricturing phenotype was associated with a lower rate of SI (7%) compared to inflammatory (48%) or penetrating phenotypes (45%). Disease activity, noted by clinical scores, endoscopic disease activity, or radiographic disease activity, were not associated with SI (Table 2). On multivariable analysis, only back pain was associated with SI (OR 3.01, 95% CI; P = 0.04). CONCLUSION: SI is a common comorbid condition in CD, but often underdiagnosed. With limited clinical clues and disease characteristics to suggest SI, physicians may utilize MRE for clinical activity to assess for SI. Data suggest targeted screening of patients with back pain.