Vitamin D level and sustained virologic response to interferon-based antiviral therapy in chronic hepatitis C: a systematic review and meta-analysis

Background Aims The baseline 25-hydroxyvitamin D (25[OH]D) level has recently been reported to be an independent predictor of sustained virologic response (SVR) to treatment with pegylated interferon (PEG-IFN) plus ribavirin (RBV) for chronic hepatitis C virus (HCV) infection. However, studies have yielded inconsistent results. Thus, we conducted a systematic review and meta-analysis to clarify any association between baseline 25(OH)D level and SVR in HCV therapy. Methods Two reviewers searched four electronic databases (Medline, Embase, PubMed, and Cochrane trials register) and relevant international conference proceedings up to March 2014 for studies treating chronic HCV infection with PEG-IFN plus RBV where baseline 25(OH)D level was tested. Studies involving patients with HIV co-infection, previous liver transplantation or those receiving vitamin D supplementation were excluded. The mean baseline 25(OH)D level was compared between those who achieved and those who failed to achieve SVR. Pooled standard difference in mean 25(OH)D level, odds ratios (OR) and 95 confidence intervals (CI) were calculated with the Comprehensive Meta-Analysis software (version 2.0) using a random effects model. Results 11 studies comprising 2605 patients were included in the meta-analysis. There was no significant association between the baseline mean 25(OH)D level and SVR (OR 1.44, 95 CI 0.92-2.26; p = 0.11), either in patients infected with genotypes 1/4/5 (OR 1.48, 95 CI 0.94-2.34; p = 0.09) or genotypes 2/3 (OR 1.51, 95 CI 0.26-8.87; p = 0.65). Conclusions The baseline 25(OH)D level is not associated with SVR to PEG-IFN plus RBV therapy in chronic HCV infection, regardless of genotype. Any effect of vitamin D supplementation on SVR is yet to be definitively determined.