The Risk of Later Diagnosis of Inflammatory Bowel Disease in Patients With Dermatological Disorders Associated With Inflammatory Bowel Disease

Background: Dermatological conditions such as erythema nodosum (EN), pyoderma gangrenosum, Sweet's syndrome, and aphthous stomatitis can occur with inflammatory bowel disease (IBD) and are considered dermatological extraintestinal manifestations (D-EIMs). Rarely, they may precede IBD. Other common conditions such as psoriasis have also been associated with IBD.This study examined the risk of a subsequent IBD diagnosis in patients presenting with a D-EIM. Methods: A retrospective cohort study compared patients with D-EIMs and age-/sex-matched patients without D-EIMs. Hazard ratios (HRs) were adjusted for age, sex, body mass index, deprivation, comorbidity, smoking, loperamide use, anemia, and lower gastrointestinal symptoms. Logistic regression was used to produce a prediction model for the diagnosis of IBD within 3 years of EN diagnosis. Results: We matched 7447 patients with D-EIMs (74% female; median age 38 years (interquartile ratio [IQR], 24-65 years) to 29,297 patients without D-EIMs. We observed 131 (1.8%) subsequent IBD diagnoses in patients with D-EIMs compared with 65 (0.2%) in those without D-EIMs. Median time to IBD diagnosis was 205 days (IQR, 44-661 days) in those with D-EIMs and 1594 days (IQR, 693-2841 days) in those without D-EIMs. The adjusted HR for a later diagnosis of IBD was 6.16 (95% confidence interval [CI], 4.53-8.37; P < 0.001), for ulcerative colitis the HR was 3.30 (95% CI, 1.98-5.53; P < 0.001), and for Crohn's disease the HR was 8.54 (95% CI, 5.74-12.70; P < 0.001). Patients with psoriasis had a 34% increased risk of a subsequent IBD diagnosis compared with the matched control patients (HR, 1.34; 95% CI, 1.20-1.51; P < 0.001). We included 4043 patients with an incident EN diagnosis in the prediction model cohort, with 87 patients (2.2%) diagnosed with IBD within 3 years. The model had a bias-corrected c-statistic of 0.82 (95% CI, 0.78-0.86). Conclusions: Patients with D-EIMs have a 6-fold increased risk of a later diagnosis of IBD. Younger age, smoking, low body mass index, anemia, and lower gastrointestinal symptoms were associated with an increased risk of diagnosis of IBD within 3 years in patients with EN.