Figure 1

Estimation of physiologic ability and surgical stress. Preoperative risk score (PRS): -0.0686 + 0.00345X1 + 0.323X2 + 0.205X3 + 0.153X4 + 0.148X5 + 0.0666X6; X1, age; X2, presence (1) or absence (0) of severe heart disease; X3, presence (1) or absence (0) of severe pulmonary disease; X4, presence (1) or absence (0) of diabetes mellitus; X5, performance status index (0 to 4); X6, American Society of Anesthesiologists physiologic status classification (1 to 5). LLR, laparoscopic liver resection; OR, open liver resection. Surgical stress score (SSS): -0.342 + 0.0139X1 + 0.092X2 + 0.352X3; X1, blood loss/body weight (g/kg); X2, operation time (h); X3, extent of skin incision ((0) minor incision for laparoscopic or thoracoscopic surgery including scope-assisted surgery; (1) laparotomy or thoracotomy alone; (2) both laparotomy and thoracotomy). LLR, laparoscopic liver resection; OR, open liver resection. Comprehensive risk score (CRS): -0.328 + 0.936(PRS) +0.976(SSS). LLR, laparoscopic liver resection; OR, open liver resection.