A meta-analysis of N-acetylcysteine in contrast-induced nephrotoxicity: unsupervised clustering to resolve heterogeneity

<p>Abstract</p> <p>Background</p> <p>Meta-analyses of N-acetylcysteine (NAC) for preventing contrast-induced nephrotoxicity (CIN) have led to disparate conclusions. Here we examine and attempt to resolve the heterogeneity evident among these trials.</p> <p>Methods</p> <p>Two reviewers independently extracted and graded the data. Limiting studies to randomized, controlled trials with adequate outcome data yielded 22 reports with 2746 patients.</p> <p>Results</p> <p>Significant heterogeneity was detected among these trials (<it>I</it>²= 37%; <it>p </it>= 0.04). Meta-regression analysis failed to identify significant sources of heterogeneity. A modified L'Abbé plot that substituted groupwise changes in serum creatinine for nephrotoxicity rates, followed by model-based, unsupervised clustering resolved trials into two distinct, significantly different (<it>p </it>< 0.0001) and homogeneous populations (<it>I</it>²= 0 and <it>p </it>> 0.5, for both). Cluster 1 studies (<it>n </it>= 18; 2445 patients) showed no benefit (relative risk (RR) = 0.87; 95% confidence interval (CI) 0.68–1.12, <it>p </it>= 0.28), while cluster 2 studies (<it>n </it>= 4; 301 patients) indicated that NAC was highly beneficial (RR = 0.15; 95% CI 0.07–0.33, <it>p </it>< 0.0001). Benefit in cluster 2 was unexpectedly associated with NAC-induced decreases in creatinine from baseline (<it>p </it>= 0.07). Cluster 2 studies were relatively early, small and of lower quality compared with cluster 1 studies (<it>p </it>= 0.01 for the three factors combined). Dialysis use across all studies (five control, eight treatment; <it>p </it>= 0.42) did not suggest that NAC is beneficial.</p> <p>Conclusion</p> <p>This meta-analysis does not support the efficacy of NAC to prevent CIN.</p

Inpatient coronary angiography and revascularisation following non-ST-elevation acute coronary syndrome in patients with renal impairment: a cohort study using the Myocardial Ischaemia National Audit Project.

BACKGROUND: International guidelines support an early invasive management strategy (including early coronary angiography and revascularisation) for non-ST-elevation acute coronary syndrome (NSTE-ACS) in patients with renal impairment. However, evidence from outside the UK suggests that this approach is underutilised. We aimed to describe practice within the NHS, and to determine whether the severity of renal dysfunction influenced the provision of angiography and modified the association between early revascularisation and survival. METHODS: We performed a cohort study, using multivariable logistic regression and propensity score analyses, of data from the Myocardial Ischaemia National Audit Project for patients presenting with NSTE-ACS to English or Welsh hospitals between 2008 and 2010. FINDINGS: Of 35 881 patients diagnosed with NSTE-ACS, eGFR of 90 ml/minute/1.73 m(2), patients with an eGFR between 45-59 ml/minute/1.73 m(2) were 33% less likely to undergo angiography (adjusted OR 0.67, 95% CI 0.55-0.81); those with an eGFR<30/minute/1.73 m(2) had a 64% reduction in odds of undergoing angiography (adjusted OR 0.36, 95%CI 0.29-0.43). Of 16 646 patients who had inpatient coronary angiography, 58.5% underwent inpatient revascularisation. After adjusting for co-variables, inpatient revascularisation was associated with approximately a 30% reduction in death within 1 year compared with those managed medically after coronary angiography (adjusted OR 0.66, 95%CI 0.57-0.77), with no evidence of modification by renal function (p(interaction) = 0.744). INTERPRETATION: Early revascularisation may offer a similar survival benefit in patients with and without renal dysfunction, yet renal impairment is an important determinant of the provision of coronary angiography following NSTE-ACS. A randomised controlled trial is needed to evaluate the efficacy of an early invasive approach in patients with severe renal dysfunction to ensure that all patients who may benefit are offered this treatment option