This is consistent with our findings in the study. The pooled incidence for AKI in the statin

group was higher than the nonstatin group (6.13% vs. 4.28%). The effect of preoperative statin on postoperative AKI was insignificant in pooled crude analysis (pooled OR, 0.98; 95% CI 0.82–1.18, I2 = 87.7%), but turned significant in pooled adjusted (pooled OR, 0.86; 95% CI 0.78–0.95, I2 = 69.4%) and PSM analyses (pooled OR, 0.83; 95% CI 0.75–0.92, I2 = 67.1%). A similar condition presented in the analysis of preoperative statin on postoperative AKI requiring RRT. The pooled crude analysis showed a paradoxical harmful effect of statin therapy (pooled OR, 1.46; 95% CI 1.31–1.62, I2 = 48.4%), while the adjusted (pooled OR, 0. 81; 95% CI 0.72–0.91, I2 = 0.0%) this website and PSM analyses (pooled OR, 0.81; 95% CI 0.72–0.92, I2 = 0.0%) showed significant protective effects of statin therapy. The different results of crude versus adjusted and PSM analyses reflected the importance of the methodological quality

of studies. The subgroup analysis of the five RCTs showed a non-significant protective effect on postoperative AKI (pooled OR, 0.49; 95% CI 0.22–1.09, I2 = 0.0%). There were several possible explanations for the null effect of these studies of the theoretically highest methodological quality. First, the pooled sample size was only 467 and the total events of AKI were 19 (8%) and 29(12.5%). The small sample size may be underpowered to detect the protective effect of statin. Second, postoperative AKI was prespecified as a primary endpoint in only one out of the NVP-AUY922 order five RCTs. Other studies

reported postoperative AKI as a secondary outcome or merely reported the number of events without prespecified outcome definition. The accuracy of the record might be questioned. Third, the definition for postoperative AKI differs a lot in these five studies. In two studies,[25, 27] no clear definition for postoperative AKI was provided. Liakopoulos OJ et al. had conducted a systemic review and meta-analysis based on RCTs.[21] They ifoxetine included four RCTs[24-27] and a total of 367 participants were analyzed for the effect of preoperative statin on postoperative renal outcome. The assessed renal outcome, renal failure, had an incidence of 3.2% in the statin group and 7.1% in the control group. In correspondence to our result, they reported a non-significant protective effect (pooled OR, 0.41; 95% CI 0.15–1.12, P = 0.08) from pooled analysis with a fixed effect model. The pooled crude incidence of postoperative AKI and postoperative AKI requiring RRT were 4.89% and 0.94%, respectively (Table 2). These results were consistent with previous report for incidence of postoperative AKI and AKI requiring RRT,[1-4] which ranged 1–30% and 0.7–1.4%, respectively.