Complementary role of vitamin D deficiency and the interleukin-28B rs12979860 C/T polymorphism in predicting antiviral response in chronic hepatitis C

Abstract

The widely accepted interleukin‐28B (IL‐28B) rs12979860 C/T polymorphism and the more recently proposed vitamin D serum concentration are two novel predictors of the response to antiviral treatment in chronic hepatitis C virus (HCV) infection. This study aimed to verify whether the IL‐28B rs12979860 C/T polymorphism and pretreatment serum vitamin D levels have independent or complementary roles in predicting the rates of sustained viral response (SVR). The present study included 211 consecutive, treatment‐naïve chronic HCV patients who had their pretreatment serum 25‐OH vitamin D level and IL‐28B rs12979860 C/T genotype determined. Overall, SVR was achieved by 134/211 (63.5%) patients and by 47/110 (42.7%) patients infected with difficult‐to‐treat HCV genotypes. On multivariate analysis, SVR was predicted by the HCV genotype, the IL‐28B rs12979860 C/T polymorphism, and gamma‐glutamyl transpeptidase, HCV RNA, cholesterol, and 25‐OH vitamin D serum levels, with an area under the receiver operating characteristic (ROC) curve of 0.827. When difficult‐to‐treat HCV genotypes were analyzed separately, the SVR was predicted by the IL‐28B rs12979860 C/T polymorphism, viral load, and serum vitamin D level, with an area under the ROC curve of 0.836. Moreover, by categorizing these latter patients into four groups—C/C homozygotes with vitamin D levels >20 ng/mL (group A) or ≤20 ng/mL (group B) and C/T heterozygotes or T/T homozygotes with vitamin D levels >20 ng/mL (group C) or ≤20 ng/mL (group D)—a significant linear trend was observed, with SVR rates in the following descending order: group A, 18/21 (85.7%); group B, 6/11 (54.5%); group C, 14/38 (36.8%); and group D, 9/40 (22.5%) (P < 0.0001). Conclusion: Vitamin D serum levels are complementary to the IL‐28B rs12979860 C/T polymorphism in enhancing the correct prediction of the SVR in treatment‐naïve chronic hepatitis C. (HEPATOLOGY 2011;)