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Protective effects of anti-oxidant supplementations on contrast-induced nephropathy after coronary angiography: an updated and comprehensive meta-analysis and systematic review.

BACKGROUND AND AIM
This systematic review with meta-analysis sought to determine the strength of evidence for effects of antioxidants (AO) such as N-acetyl cysteine (NAC), vitamin C, vitamin E, and alpha-lipoic acid on the incidence of contrast-in-duced nephropathy (CIN), requirement for haemodialysis, level of serum creatinine, and mortality after coronary angiography.


METHODS AND RESULTS
After Medline, Embase, Elsevier, Sciences online database, and Google Scholar literature searches, studies with randomised controlled design were selected for the meta-analysis. The effect sizes measured were odds ratio (OR) for categorical variables and standard mean difference (SMD) with 95% confidence interval (CI) for calculating differences between mean changes of serum creatinine in intervention and control groups. A value of p < 0.1 for Q test or I2 > 50% indicated significant heterogeneity between the studies. Literature search of all major databases retrieved 2350 studies. After screening, a total of 49 trials were identified that reported outcomes. Pooled treatment effect analysis revealed that NAC (OR of 0.79; 95% CI 0.69-0.9; p = 0.000), vitamin C (0.63; 95% CI 0.45-0.89; p = 0.000), and vitamin E (OR of 0.5; 95% CI 0.27-0.92; p = 0.026) could significantly reduce the incidence of CIN. NAC (SMD of -0.119; 95% CI -0.191 - 0.046; p = 0.000), but not vitamin C (SMD of -0.08; 95% CI -0.22-0.04; p = 0.1) and vitamin E (-0.25; 95% CI -0.46-0.05; p = 0.1), could significantly reduce mean levels of serum creatinine. Nevertheless, AO could not reduce the incidence of mortality, with an OR of 0.94 (95% CI 0.69-1.28; p = 0.7).


CONCLUSIONS
Overall, antioxidants such as NAC, vitamin C, and vitamin E can reduce the incidence of CIN, while only NAC might be able to significantly lower serum creatinine levels. There is no impact of AO supplementation on mortality.