Table 3. Absolute and relative risks associated with high- and low-risk groups for acute kidney injury onset within the first seven days after surgery stratified by predictive model.

	Absolute risk % a (95% Confidence Interval)		Relative risk b (95% Confidence Interval)
Models	Low-risk groupc	High-risk groupc	High- vs low-risk group
Preoperative model	21.5% (18.1%, 25.02%)	72.6% (67.8%, 77.3%)	3.4 (2.8, 4.0)
Postoperative stacked model	15.6% (12.3%, 18.9%)d	71.3% (66.9%, 75.7%)	4.6 (3.7, 5.7)
Postoperative full model	14.6% (11.4%, 17.7%)d	74.1% (69.7%, 78.4%)	5.1 (4.1, 6.4)

^a Absolute risk was calculated as the percentage of cases for which acute kidney injury occurred in the low- and high-risk groups, respectively.

^b Relative risk was calculated as the ratio of the absolute risk of the occurrence of acute kidney injury between the high- and low-risk groups.

^c Patients were classified as low-risk if their prediction score was less than or equal to cutoff and high-risk otherwise. The cutoff values were 0.43, 0.41, and 0.40 for preoperative model, postoperative stacked model, and postoperative full model, respectively. The cutoffs were determined using the maximum value of Youden Index.

^d Significantly different from preoperative model with adjusted p-value ≤ 0.05 when absolute risk of all pairs of three models were compared using the Bonferroni method.