On multivariate logistic regression analysis, predictors of any complication in derivation cohort include age ≥65 years, female gender, emergency admission, CAD, coagulopathy, CLD, CKD, CVA, and PVD, which constituted our ‘risk score model’ (see Table 3). Hypertension, diabetes, obesity, CHF, and COPD were significant predictors on univariate, but not on multivariate analysis. The assigned risk score (in parenthesis) for each of these multivariate predictors in the descending order of significance include CKD (5), coagulopathy (5), CLD (5), CVA (3), emergency procedure (3), age ≥ 65 years (2), CAD (2), PVD (1), and female gender (1) with a combined total score of 27. The whole cohort was divided into four groups based on the combined total score: Group 0 with the risk score of 0, Group 1 with risk score from 1 to 5, Group 2 with risk score from 6 to 10, and Group 3 with risk score from 11 to 27. Group 3 includes wider range of scores from 11 to 27 due to the progressively fewer number of patients at higher risk scores. The comparison of complication rates by risk score groups in whole sample were depicted in Table 4 and Figure 1 and in validation cohort were depicted in Supplementary material online, Appendix (Table 7, Figures 3 and 4).