HMG CoA reductase inhibitors (statins) for preventing acute kidney injury after surgical procedures requiring cardiac bypass.

Abstract

Background Acute kidney injury (AKI) is a common complication of cardiac surgery, with incidence ranging from 1-30%. Cardiac associated AKI has been shown to increase morbidity and mortality, is associated with longer intensive care stays and increased cost, especially when renal replacement therapy (RRT) is required. Cardiopulmonary bypass has been identified as a significant risk factor for AKI. Overall decrease in blood flow has been shown to decrease glomerular filtration rate, but it is also thought that cardiopulmonary bypass triggers an inflammatory response that injures kidney tissue. Statins are widely used as lipid lowering drugs. However they have also been shown to have an anti-inflammatory effect, with some evidence that statin administration prior to cardiac surgery reduces peri procedural cardiovascular events. There is an urgent need for effective therapies in this group because kidney dysfunction after surgery leads to significant morbidity compared to patients who maintain normal kidney function. Evidence indicating that statins help to prevent kidney injury will help to address the gap that exists in effective therapies in the setting of cardiac surgery requiring cardiopulmonary bypass. Objectives To determine whether use of statins was associated with preventing AKI development, determine whether the use of statins was associated with reductions in in-hospital mortality and determine whether the use of statins was associated with reduced need for RRT. Interventions/methods Randomised controlled trials that compared administration of statin therapy with placebo or standard clinical care in adults undergoing surgery requiring cardiopulmonary bypass, and reporting AKI, serum creatinine (SCr) or need for RRT as an outcome were eligible for inclusion. The dose or type of statins used was not restricted. Studies that included patients undergoing cardiac surgery but did not require bypass were excluded. Results Seven studies (662 participants) were included in this review. All except one study was assessed as being at high risk of bias. Three studies assessed atorvastatin, three assessed simvastatin and one investigated rosuvastatin. All studies collected data during the immediate perioperative period only; data collection to hospital discharge and postoperative biochemical data collection ranged from 24 hours to 7 days. Overall, preoperative statin treatment was not associated with a reduction in postoperative AKI, need for RRT or reduction in in-hospital mortality. Only two studies (195 participants) reported postoperative SCr level. In those studies, patients allocated to receive statins had lower postoperative SCr concentrations compared with those allocated to no drug treatment/placebo (MD 21.2 µmol/L, 95% CI -31.1 to-11.1). Adverse effects were adequately reported in only one study; no difference was found between the statin groups compared to placebo. Conclusions Currently available data does not indicate that preoperative statin use is associated with decreased incidence of AKI in adults who required cardiac bypass. A significant reduction in SCr was seen postoperatively in people treated with statins, these results were driven by a single study, with SCr reported as a secondary outcome, meaning there is significant uncertainty regarding the strength of this result. The results of the meta-analysis should be interpreted with caution, few studies were included in subgroup analyses, and significant differences in methodology exist among the included studies. Overall no reduction in mortality or need for RRT was seen in people receiving statin therapy undergoing cardiac surgery requiring bypass.