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.