The development and validation of risk-stratification models for short-term outcomes following contaminated complex abdominal wall reconstruction

Background: Short-term outcomes for patients undergoing contaminated complex abdominal wall reconstruction (CCAWR), including risk stratification, have not been studied in sufficiently high numbers. This study aims to develop and validate risk-stratification models for Clavien–Dindo (CD) grade ≥ 3 complications in patients undergoing CCAWR. Methods: A consecutive cohort of patients who underwent CCAWR in two European national intestinal failure centers, from January 2004 to December 2015, was identified. Data were collected retrospectively for short-term outcomes and used to develop risk models using logistic regression. A further cohort, from January 2016 to December 2017, was used to validate the models. Results: The development cohort consisted of 272 procedures performed in 254 patients. The validation cohort consisted of 114 patients. The cohorts were comparable in baseline demographics (mean age 58.0 vs 58.1; sex 58.8% male vs 54.4%, respectively). A multi-variate model including the presence of intestinal failure (p < 0.01) and operative time (p < 0.01) demonstrated good discrimination and calibration on validation. Models for wound and intra-abdominal complications were also developed, including pre-operative immunosuppression (p = 0.05), intestinal failure (p = 0.02), increasing operative time (p = 0.04), increasing number of anastomoses (p = 0.01) and the number of previous abdominal operations (p = 0.02). While these models showed reasonable ability to discriminate patients on internal assessment, they were not found to be accurate on external validation. Conclusion: Acceptable short-term outcomes after CCAWR are demonstrated. A robust model for the prediction of CD ≥ grade 3 complications has been developed and validated. This model is available online at www.smbari.co.uk/smjconv2.