Validation of a left-sided colectomy anastomotic leak risk score and assessment of diversion practices.

Background: A left-sided anastomotic leak risk score was previously developed and internally but not externally validated.

Methods: Left-sided colectomy anastomotic leak risk scores were calculated for patients within the ACS NSQIP Colectomy Targeted PUF from 2017 to 2018 and institutional NSQIP databases at three hospitals from 2011 to 2019. The calibration and discrimination of the risk score was assessed.

Results: A total of 21,116 patients (ACS NSQIP) and 485 patients (institutional NSQIP) were identified. Anastomotic leak rate was 2.8% and 2.9% respectively. C-statistic in the ACS NSQIP cohort was 0.61 and 0.64 in the institutional cohort compared to 0.66 in the original development cohort. Strong visual correspondence existed between predicted and observed anastomotic leak rates in the ACS NSQIP cohort.

Conclusions: The left-sided anastomotic leak risk score was validated in two new populations. Use of the score would aid in the decision of when to perform a diverting stoma.