Clinical trials evaluating acetylcysteine for the prevention of contrast-related nephropathy have reported mixed results. Although previous meta-analyses have concluded that acetylcysteine is beneficial, the recent availability of additional trials calls for reassessment of current evidence. We performed a computerized search to identify relevant published and unpublished randomized clinical trials that evaluated acetylcysteine for the prevention of contrast-related nephropathy. Abstracted data from each trial included assessments of clinical outcomes, trial quality, and additional characteristics. The primary outcome of interest was the incidence of nephropathy after contrast administration. Data were combined using random-effects models with the performance of standard tests to assess for heterogeneity and publication bias. Subgroup analyses were also performed. Twenty trials involving 2195 patients met our inclusion criteria. Trials varied in patient demographic characteristics, inclusion criteria, dosing regimens, and trial quality. The summary risk ratio for contrast-related nephropathy was 0.73 (95% confidence interval: 0.52 to 1.0; P = 0.08), a nonsignificant trend towards benefit in patients treated with acetylcysteine. This effect varied, however, across the 20 trials (test of heterogeneity, P = 0.04). Although higher-quality trials demonstrated a stronger benefit for acetylcysteine in general, few reported important elements of study design, such as concealment of allocation, placebo-controls, or double-blinding. Heterogeneity was unexplained by subgroup analyses. Acetylcysteine may reduce the incidence of contrast-related nephropathy, but this finding is reported inconsistently across currently available trials. High-quality, large clinical trials are needed before acetylcysteine use in this indication can be recommended universally.
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