Association between serum vitamin D and severity of liver fibrosis in chronic hepatitis C patients: a systematic meta-analysis.

To conduct a systematic review of group studies assessing the association of serum vitamin D status with the severity of liver fibrosis in chronic hepatitis C patients using meta-analysis. The relevant research literatures were identified by searching PubMed and EMBASE databases prior to October 2013 with no restrictions. We included group studies that reported odds ratio (OR) estimates with 95% confidence intervals (CIs) or a mean with standard deviation (SD) for the association between serum vitamin D status and the severity of liver fibrosis in chronic hepatitis C patients. Approximately 8321 participants from several countries were included in this analysis. Six studies on serum vitamin D status and the severity of liver fibrosis were included in this meta-analysis. ORs with 95% CIs were extracted from four studies and the pooled ORs were 0.866 (95% CI, 0.649 to 1.157). The means with SDs were extracted from three studies and the pooled means were -0.487 (95% CI, -0.659 to -0.315). There was statistically significant heterogeneity among the mean data extracted studies (P=0.029; I(2)=71.8%) but not among the OR data extracted studies (P=0.061; I(2)=55.6%). Finally, results from the mean data extracted studies suggest that lower serum vitamin D is a risk factor for the severity of liver fibrosis in chronic hepatitis C patients. However, there is no conclusive evidence on this association because of inconsistencies between the OR data extracted studies and the mean data extracted studies.