Twenty-two studies (27,806 participants) were included: six RCTs (498 participants) and 16 observational studies (6,600 participants in OPCAB group and 20,708 in the coronary artery bypass group). Three RCTs and five observational studies were considered to be of good quality.
Compared to coronary artery bypass, OPCAB reduced the incidence of acute kidney injury (OR 0.57, 95% CI 0.43 to 0.76, I2=67%; five RCTs and 14 observational studies). When analysed separately, observational studies and RCTs gave similar results to the main analysis.
OPCAB reduced the incidence of acute kidney injury that required RRT (OR 0.55, 95% CI 0.43 to 0.71, I2=0%; five RCTs and 13 observational studies). Results for observational studies were similar to the main analysis. Results for RCTs showed no statistically significant difference between groups.
Compared to coronary artery bypass, peak postoperative serum creatinine was lower in the OPCAB group (WMD -0.08, 95% CI -0.14 to -0.02, I2=28.1%; one RCT and five observational studies). There was no statistically significant difference in effect in the RCT. There was no difference in preoperative to postoperative changes in levels of serum creatinine (two observational studies) and changes in creatinine clearance (one observational study).
Sensitivity analyses of studies that included participants with pre-existing renal insufficiency showed a reduction in acute kidney injury (OR 0.47, 95% CI 0.32 to 0.70, I2=17.7%; six studies) and acute kidney injury that required RRT (OR 0.43, 95% CI 0.23 to 0.80, I2=0%; five studies).
Good quality studies alone found a reduction in acute kidney injury and in requirement for RRT therapy (three RCTs and five observational studies).