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

Evidence suggests that obesity (body mass index (BMI) > 30 kg/m²) 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.

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.

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).

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.