S1973 Tobacco Use Predicts Disease Behavior and Localization in Perianal Fistulizing Crohn’s Disease: A Retrospective Cohort Study

Introduction: Although tobacco use is a well-recognized risk factor for severe Crohn’s disease (CD) phenotypes, its impact on patients with perianal fistulizing CD (PFCD) remains incompletely defined. This study aims to assess the relationship between tobacco use and disease behavior, localization, and outcomes in patients with PFCD. Methods: We identified 182 CD patients from a quaternary care center, diagnosed with PFCD between 2005-2025. Demographics, disease features, and healthcare use data after CD diagnosis were collected via retrospective chart review. Univariate and multivariate regression models were used, adjusted for age, gender, and time observed. Disease course 1 year after diagnosis was classified as remission (no further abscess or drainage), continuous drainage (light and heavy) or ≥2 distinct flares. Results: Mean participant age was 30.4 (SD 11.36). Of the subjects, 58.2% (n = 106) were men, 68.7% (n = 125) never smoked, 22.5% (n = 41) formerly smoked and 8.8% (n = 16) currently smoked. 95.6% (n = 174) used biologics and 68% (n = 123) used immunomodulators. Mean ED visits were 1.66 (SD 2.36), exams under anesthesia (EUA) 2.98 (SD 2.6), and proctectomies/diversions 1.31 (SD 0.784). Within 1 year of PAF diagnosis, 19.2% (n = 35) achieved remission, 6.6% (n = 12) had light drainage, 19.8% (n = 10) had heavy drainage, and 48.9% (n = 89) had flares. Disease localized to L1 in 22.2% (n = 40), L2 in 28.1% (n = 53), and L3 in 47.8% (n = 87). Univariate analysis showed an association between tobacco use and location (P = 0.009), course (P = 0.043) and diversions/proctectomies (P = 0.011). In multivariate analysis, patients with tobacco exposure were more likely to have L2 over L1 disease (OR 4.31; CI 1.42–14.23; P = 0.010). In year 1, smokers were likely to have ≥2 flares over remission (OR 3.56; CI 1.24–10.19; P = 0.018). Active smokers exceeded the average number of EUA (OR 4.15; CI 1.39 – 12.4, P = 0.010), had 1.27 more ED visits (P = 0.047), and had 0.42 more diversions/proctectomies (P = 0.048) than never-smokers. Conclusion: This study shows that tobacco exposure was associated with L2 disease in our PFCD cohort, contrasting prior studies linking smoking to L1 and L3 in the general CD population. PFCD patients with tobacco exposure were more likely to have perianal disease flares in the first year, increased healthcare use and need for diversion surgery. Our findings support prior evidence linking smoking to complicated CD and highlight its role in risk stratification and expectant management of PFCD.