Establishment and evaluation of risk prediction model of anal incontinence after complex anal fistula surgery

Abstract:

Objective To establish a risk prediction model of anal incontinence after complex anal fistula surgery and evaluate its effect.Methods The data of 195 patients with complex anal fistula admitted to the Anorectal Department of The People's Hospital Affiliated to Fujian University of Traditional Chinese Medicine from January 2020 to May 2021 were analyzed retrospectively. According to the symptoms of postoperative anal incontinence，the patients with CCFIS score ≥ 2 points were divided into anal incontinence group （42 cases），and the patients with CCFIS score<2 points were divided into normal function group（153 cases）. Univariate and logistic regression analysis was carried out in combination with the general situation of patients， fistula nature， anorectal manometry measurement results，surgical methods and other variables.Results The incidence of postoperative anal incontinence was 21.54%，and the average score of CCFIS was 3.40±1.170. Logistic regression analysis showed that the fistula type was supra-sphincter fistula（OR=1.024，95%CI=0.405–2.585，P=0.025），previous anal fistula surgery > 1 time in the past（OR=16.224，95%CI=3.291–29.977，P=0.001），low resting pressure（OR=0.909，95%CI=0.869–0.952，P=0.000），and the operation method was cutting seton（OR=1.389，95%CI=1.044–1.848，P=0.024），which were independent risk factors of the anal incontinence after complex anal fistula surgery（P<0.05）. According to the screened independent risk factors，the prediction model was constructed and the ROC curve was drawn. The area under the curve（AUC） was 0.879（95%CI=0.818-0.939，P<0.001），suggesting a good prediction value of the model.Conclusion The prediction model established by independent risk factors has high accuracy， and provides a good reference for the formulation of clinical treatment plan for complex anal fistula.