Randomised controlled trials (RCTs) in patients aged over 19 years of age with all degrees of renal function undergoing cardiac surgery (coronary artery bypass grafting and/or valve surgery; elective, emergent or not specified) compared with no therapy, placebo or standard care for the institution (such as maximal hydration) were eligible for inclusion. Studies were eligible if kidney injury was assessed by methods of serum creatinine or creatinine clearance/glomerular filtration rate (GFR). Eligible interventions included methods of prevention or treatment of acute kidney injury administered any time before, during or after surgery and included medical therapies as well as procedure-based therapies (such as cardiopulmonary bypass modification and early renal replacement therapy). Relevant outcomes included incidence of acute kidney injury or change in serum creatinine, creatinine clearance, glomerular filtration rate, incidence of acute renal replacement therapy and mortality. Renal outcomes were abstracted regardless of whether they were a primary or secondary trial outcome. Studies that described outcomes for patients who were on renal replacement therapy prior to surgery or who had received a kidney transplant were excluded.
In the included studies, acute kidney injury definitions varied. Criteria for the initiation of acute renal replacement therapy were not comparable across studies. Some studies included patients with chronic kidney disease. Studies analysed the effects of vasodilators, interventions that primarily induced natriuresis or diuresis or both, anti-inflammatory agents and interventions that worked through other mechanisms of action. Interventions were given preoperatively, intraoperatively and postoperatively. Where reported, frequency of assessing kidney function was variable between studies (range eight hours to measurements on days one, five and 15), Studies were in 21 countries. Sixty-four studies involved coronary artery bypass grafting and 27 involved valvular surgeries. Mean age ranged from 35.1 to 82.5 years. In most studies the proportion of males was over 50%.
Two reviewers independently selected studies for inclusion in the review.