Quantification of risk for pouch failure after ileal pouch anal anastomosis surgery

Abstract

Objective: To identify risk factors associated with ileal pouch failure and to develop a multifactorial model for quantifying the risk of failure in individual patients. SUMMARY BACKGROUND DATA Ileal pouch anal anastomosis (IPAA) has become the treatment choice for most patients with ulcerative colitis and familial adenomatous polyposis who require surgery. At present, there are no published studies that investigate collectively the interrelation of factors related to ileal pouch failure, nor are there any predictive indices for risk stratification of patients undergoing IPAA surgery.

Methods: Data from 23 preoperative, 7 intraoperative, and 10 postoperative risk factors were recorded from 1,965 patients undergoing restorative proctocolectomy in a single center between 1983 and 2001. Primary end point was ileal pouch failure during the follow-up period of up to 19 years. The "CCF ileal pouch failure" model was developed using a parametric survival analysis and a 70%:30% split-sample validation technique for model training and testing.

Results: The median patient follow-up was 4.1 year (range, 0-19 years). Five-year ileal pouch survival was 95.6% (95% CI, 94.4-96.7). The following risk factors were found to be independent predictors of pouch survival and were used in the final multivariate model: patient diagnosis, prior anal pathology, abnormal anal manometry, patient comorbidity, pouch-perineal or pouch-vaginal fistulae, pelvic sepsis, anastomotic stricture and separation. The model accurately predicted the risk of ileal pouch failure with adequate calibration statistics (Hosmer Lemeshow chi2 = 3.001; P = 0.557) and an area under the receiver operating characteristics curve of 82.0%.

Conclusions: The CCF ileal pouch failure model is a simple and accurate way of predicting the risk of ileal pouch failure in clinical practice on a longitudinal basis. It may play an important role in providing risk estimates for patients wishing to make informed choices on the type of treatment offered to them.

FIGURE 2. Probability of ileal pouch failure at 1, 2, 5, 10, and 15 years follow-up based on the CCF-IPF score as calculated by the Weibull survival model (CCF-IPF model). The individual patient probabilities are shown (diamonds).

FIGURE 3. Calibration chart of the CCF-IPF score. The observed and predicted ileal pouch failure rates are displayed along with the 95% CI around the observed outcome.

FIGURE 4. Comparison of observed and model-predicted ileal pouch failure rate by type of anastomosis on a random sample of 1000 patients.

FIGURE 5. Cumulative ileal pouch survival by CCF-IPF score.

FIGURE 1. Variation of pouch failure rate by year of pouch construction (bar chart). The annual workload of ileal pouch procedures at the Cleveland Clinic Foundation is also shown (line chart).