N-acetylcysteine to reduce renal failure after cardiac surgery: a systematic review and meta-analysis

Abstract

To assess the effect of N-acetylcysteine (NAC) on acute renal failure and important clinical outcomes after cardiac surgery. Two reviewers performed literature searches, using EMBASE and PubMed, of randomized controlled trials investigating the renoprotective effect of N-acetylcysteine in cardiac surgery. Treatment effects were calculated as relative risks (RR) with 95% confidence intervals (CI). Heterogeneity and publication bias were assessed using the I(2) test and funnel plots, respectively. Meta regression was performed to assess the effect of baseline renal function and the use of aprotinin on renal function. Seven randomized controlled trials (RCTs) (n = 1000) were identified. No study could demonstrate, either independently or meta-analytically, an improvement in the postoperative increase in creatinine, mortality (RR 0.93, 95% CI 0.4 to 2.07), renal failure requiring renal replacement therapy (RR 1.01, 95% CI 0.49 to 2.12), myocardial infarction (RR 0.88, 95% CI 0.36 to 1.88), atrial fibrillation (RR 0.88, 95% CI 0.70 to 1.10), or stroke (RR 0.69, 95% CI 0.27 to 1.69). There was a small, though significant increase in postoperative blood loss among patients treated with NAC (weighted mean difference 119 mL 95% CI 51, 187). After meta regression neither increase in postoperative creatinine (r(2) = 0.33) nor renal replacement therapy (r(2) = 0.04) was associated with the baseline creatinine or with NAC dose (r(2) =0.04). This analysis did not find that treatment with NAC was associated with clinical renal protection during cardiac surgery, or improvement in other clinical outcomes.