[Prophylaxis of contrast-induced nephropathy with N-acetylcysteine]

Clinical trials evaluating N-acetylcysteine (NAC) for the prevention of radiocontrast-induced nephropathy (RCN) have reported mixed results. Despite formerly published meta-analyses and due to currently published RCTs, time has come to re-evaluate the current evidence of preventing RCN by administering NAC.

We performed a computerized search without restricted to a language to identify relevant published randomized clinical trials that evaluated N-acetylcysteine for the prevention of radiocontrast-induced 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-eight trials involving 3 604 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 0.69 (95 % confidence interval: 0.57 to 0.82; P = 0.02), a statistically significant trend towards benefit in patients treated with N-acetylcysteine. This effect varied, however, across the 28 trials, and only eight of the 28 trials demonstrated significant results although higher-quality trials demonstrated a stronger benefit for N-acetylcysteine in general, few reported important elements of study design, such as concealment of allocation, placebo-controls, or double-blinding. Heterogenity was unexplained by subgroup analyses.

N-acetylcysteine (NAC) may reduce the incidence of contrast-related nephropathy, but this finding is reported inconsistently across currently available trials. Large high-quality, clinical trials are needed before the application of N-acetylcysteine can be recommended in general for this indication.