Alpha-tocopherol and contrast-induced nephropathy: A meta-analysis of randomized controlled trials

Background: Contrast-induced nephropathy (CIN) is a relevant cause of acute renal dysfunction and is associated with an increased morbidity and mortality. Purpose: Verify the effect of α-tocopherol pre-treatment on CIN prevention in subjects with chronic kidney disease. Methods: A Medline/Embase and clinicaltrials.gov were searched up to May 1st, 2017. Randomized controlled trials recruiting patients undergoing diagnostic or therapeutic radiocontrast infusion comparing the effect of either oral or i.v. multiple administration of pharmacological dose of α-tocopherol in preventing CIN versus placebo were included. A random-effects model, calculating Mantel-Haenszel odds ratio with 95% confidence interval, was applied to study the effect of α-tocopherol on CIN occurrence. Funnel plot analysis was used to assess publication bias, while agreement within studies was measured by the I² index and tested with the Q-Cochran test. Results: Out of 242 studies, 4 trials were selected. CIN incidence resulted significantly lower in α-tocopherol compared to placebo group (5.8% vs. 15.4%, MH-OR [95% C.I.] 0.34 [0.19 - 0.59]). Alpha-tocopherol treatment was associated with both a tendential higher eGFR (mean difference 2.19 [95% C.I. -0.41; 4.79] mL/min) and lower creatinine level (mean difference -0.06 [95% C.I. -0.21; 0.09] mg/dl) compared to placebo. No relevant publication bias (p = 0.48) and heterogeneity (I² = 0%; χ² = 1.01, df = 3 [p = 0.80], I² = 0%) were evident. Conclusions: Alpha-tocopherol pre-treatment is associated with reduction of incidence of CIN. Its administration deserves to be further explored as a simple and inexpensive tool for CIN prevention.