Fig. 2

Incidence of postoperative complications in subgroups according to modified frailty index (A) and composite risk index (B). When compared with patients with mFI = 0, mFI = 0.09: P = 0.471, mFI = 0.18: P = 0.035, mFI = 0.27: P = 0.001, mFI = 0.36: P <  0.001, and mFI ≥ 0.45: P <  0.001 (chi-square tests; P <  0.003 was considered statistically significant after Bonferroni correction). When compared with patients with composite risk index of 0, composite risk index of 1: P <  0.001, composite risk index of 2: P < 0.001, composite risk index of 3 or above: P < 0.001 (chi-square tests; P < 0.008 was considered statistically significant after Bonferroni correction). Abbreviations: POCs Postoperative complications