Predictors of outcome for anal fistula surgery.

OBJECTIVES To review our experience with patients treated for anal fistula secondary to cryptoglandular disease and to determine factors that influence postoperative outcome. DESIGN Retrospective review. SETTING A regional tertiary referral center. PATIENTS Adult patients with anal fistula secondary to cryptoglandular disease. INTERVENTIONS Fistulotomy, advancement flap, and fistula plugging. MAIN OUTCOME MEASURES Rates of operative failure (persistent fistula), incontinence, and septic complications. We evaluated age, sex, previous operation, fistula type, number of fistula tracts, horseshoe fistula, and intervention type to determine their independent influence on outcomes. RESULTS One hundred seventy-nine patients (79.3% male) underwent fistula operation from October 1, 2003, through December 31, 2008. Median age was 45 years. Fistulotomy was undertaken in 82.7% of patients, advancement flap in 10.6%, and plugging in 6.7%. The rates of operative failure, postoperative incontinence, and septic complications were 15.6%, 15.6%, and 7.3%, respectively. Plugging carried the highest failure rate (83.3%) compared with fistulotomy (10.1%) (odds ratio [OR], 44.3 [95% confidence interval (CI), 8.9-221.0; P < .001]) and was the only independent predictor for failure after adjusting for all variables. Being older than 45 years was associated with a higher postoperative incontinence rate compared with the younger group (adjusted OR, 2.8 [95% CI, 1.0-7.7; P = .04]). High transsphincteric and suprasphincteric fistulas were predictors of incontinence compared with subcutaneous fistulas (adjusted OR, 22.9 [95% CI, 2.2-242.0; P = .009] and 61.5 [4.5-844.0; P = .002], respectively). The only predictor of septic complications was plugging compared with fistulotomy (adjusted OR, 15.1 [95% CI, 2.3-97.7; P = .004]). CONCLUSIONS Fistulotomy is the preferred operation for anal fistula. Plugging is associated with the highest operative failure and septic complication rates. Incontinence was influenced more by fistula type and age rather than procedure.