Obesity and Outcome of Crohn’s Associated Perianal Fistula Surgery: A Case-Control Study

BACKGROUND: Evidence suggests that obesity (body mass index (BMI) > 30 kg/m(2)) adversely affects several outcomes in Crohn’s disease (CD). CD-associated perianal fistula (CDPF) represents a debilitating phenotype with a clinical course that may be affected by obesity. We hypothesized that obese CD patients would be more likely to have poor outcomes following CDPF surgery. METHODS: We designed a case-control study of CD patients who underwent surgery for CDPF between 2000 and 2013 with documented pre-operative BMI and post-operative outcome. Cases and controls were defined based on the outcome of CDPF surgery. Poor outcomes were designated as cases. RESULTS: Of the 317 patients diagnosed with CDPF, 73 patients underwent 120 surgeries for CDPF. Eighty-nine (74%) of the surgeries comprised fistulotomy with or without Seton placement, whereas 31 (26%) were mucosal flap procedures. Twenty-five (21%) cases and 95 (79%) controls were identified. Unadjusted odds ratio (OR) for the association between obesity and outcome demonstrated a trend towards a poor surgical outcome among obese patients that did not reach statistical significance (OR: 1.86; 95% confidence interval (CI): 0.58 - 5.98; P = 0.295). Multivariable logistic regression analysis demonstrated an even stronger trend towards a poor outcome among obese CD patients, albeit without reaching statistical significance (OR: 2.83; 95% CI: 0.64 - 12.49; P = 0.169). CONCLUSION: In patients undergoing Seton placement, fistulotomy or mucosal flap procedure for CDPF, there is a trend towards poor outcomes in the obese; however, as this trend did not reach statistical significance, this association should be examined further.