Fig. 1

Receiver operating characteristic (ROC) curves for CRP ratio and CRP on postoperative day 3. We used the continuous variable density of CRP ratio (a) and CRP on postoperative day 3 (b) as the test variable and postoperative complications as the state variable. Area under ROC curve was 0.592 for CRP ratio and 0.498 for CRP on postoperative day 3. An investigation of cut-off scores showed the optimal cut-off for CRP ratio was 2.13 (sensitivity, 0.454; specificity, 0.815). We therefore set 2.13 as the cut-off for CRP ratio