Sex and the Risk of AKI Following Cardio-thoracic Surgery: A Meta-Analysis

Background and objectives Being a woman is a well established risk factor for the development of cardiothoracic surgery-associated AKI. In striking contrast, women are less likely to develop AKI associated with noncardiac surgical procedures than men. In an attempt to ascertain why being a woman might be protective for ischemic AKI after general surgery but deleterious in patients undergoing cardiothoracic surgery, we examined cardiothoracic surgery-associated AKI in greater detail. Design, setting, participants, & measurements We performed a systematic review and meta-analysis of cardiothoracic surgery-associated AKI studies published between January of 1978 and December of 2015 to further explore the relationship between sex and cardiothoracic surgery-associated AKI. Results Sixty-four studies were identified that provided sex-specific data regarding the incidence of cardiothoracic surgery-associated AKI among 1,057,412 subjects. Using univariate analysis, women were more likely than men to develop AKI postoperatively (odds ratio, 1.21; 95% confidence interval, 1.09 to 1.33; P<0.001). However, when the analysis was restricted to the 120,464 subjects reported in 29 studies that used the Acute Kidney Injury Network criteria, the RIFLE criteria, or the Kidney Disease Improving Global Outcomes criteria to define AKI, there was no significant sex-related difference in risk. Seventeen studies used multivariate analysis to assess risk factors for cardiothoracic surgery-associated AKI and provided sex-specific odd ratios. Among the 1,587,181 individuals included in these studies, the risk of developing cardiothoracic surgery-associated AKI was not significantly associated with sex (odds ratio, 1.04; 95% confidence interval, 0.92 to 1.19; P=0.51). However, when the analysis was restricted to the 5106 subjects reported in four studies that used the Acute Kidney Injury Network criteria to define AKI, the risk of developing AKI was significantly lower in women compared with in men (odds ratio, 0.75; 95% confidence interval, 0.65 to 0.87; P<0.001). Conclusions Our systematic review and meta-analysis contradict the generally held consensus that being a woman is an independent risk factor for the development of cardiothoracic surgery-associated AKI.