Relationship of Vitamin D Status With Advanced Liver Fibrosis and Response to Hepatitis C Virus Therapy: A Meta-analysis

There is growing evidence that vitamin D is related to chronic hepatitis C (CHC) pathogenicity. We analyzed the relationship of vitamin D status with advanced liver fibrosis (ALF) in CHC treatment-naive patients and sustained virologic response (SVR) in CHC patients on pegylated interferon alpha plus ribavirin (pegIFN alpha/ribavirin) therapy. We performed a meta-analysis of all eligible studies published to date (April, 2014) in PubMed, SCOPUS, LILACS, and the Cochrane Library, assessing plasma/serum vitamin D levels related to ALF and/or SVR. Pooled odds ratios (ORs) were estimated by either fixed or random effects models. Fourteen studies were selected from the literature search, seven for ALF (1,083 patients) and 11 for SVR (2,672 patients). For liver fibrosis, low vitamin D status was related to a diagnosis of ALF, with the cutoffs of 10 ng/mL (OR = 2.37, 95% confidence interval [CI] = 1.20, 4.72) and 30 ng/mL (OR = 2.22, 95% CI = 1.24, 3.97) being significant, and a near-significance for 20 ng/mL (OR = 1.44, 95% CI = 0.99, 2.12). Regarding SVR, a significant heterogeneity among studies was found (P < 0.001), and we only found a significant association with SVR for a vitamin D cutoff of 20 ng/mL (OR = 0.53, 95% CI = 0.31, 0.91). When meta-analysis was performed excluding the outliers, significant pooled ORs were found for all patients (10 ng/mL [OR = 0.48, 95% CI = 0.34, 0.67] and 20 ng/mL [OR = 0.58, 95% CI = 0.45, 0.76]) and GT1/4 patients (10 ng/mL [OR = 0.53, 95% CI = 0.34, 0.81] and 20 ng/mL [OR = 0.54, 95% CI = 0.39, 0.74]). Conclusion: Low vitamin D status in CHC patients is associated with a higher likelihood of having ALF and lower odds of achieving SVR following pegIFN alpha/ribavirin therapy.