Vitamin D Status and Virologic Response to HCV Therapy in the HALT-C and VIRAHEP-C Trials

More than 150 million people worldwide are chronically infected with hepatitis C virus (HCV) and face higher risk of cirrhosis and hepatocellular carcinoma. Highly effective HCV treatments have recently been developed; however, they are costly and therefore poorly suited for application in resource-limited settings where HCV burden is high. Pegylated-interferon alpha (PEG-IFNα) and ribavirin (RBV) therapy is far less costly, but also less effective. Vitamin D supplementation has been proposed as an inexpensive adjuvant to treatment, however, prior epidemiological evidence on its effectiveness is inconsistent, with little data available among African Americans who naturally have lower vitamin D concentrations. We thus evaluated associations between baseline vitamin D status, measured by circulating 25-hydroxyvitamin D (25(OH)D), which is considered to be the best marker of vitamin D status in humans, and subsequent response to PEG-IFNα/RBV therapy in two large clinical trials that together included 1292 patients infected with HCV genotype 1. We used race-stratified logistic regression models to evaluate multivariable-adjusted associations of 25(OH)D with early virologic response (EVR; 2-log(10) HCV RNA decline at week 12) and sustained virologic response (SVR). Among African Americans, we saw no associations. Among European Americans, we saw no association with low vitamin D (≤20 ng/mL) versus sufficient concentrations (20-<30 ng/mL). However, patients with 25(OH)D ≥30 ng/mL were actually less likely to attain EVR (OR = 0.64, 95% CI = 0.43–0.94) than those with sufficient concentrations, with a similar but non-significant association observed for SVR (OR = 0.49, 95% CI = 0.20–1.17). CONCLUSION: Higher vitamin D status was not beneficially associated with responses to therapy; if anything, patients with higher vitamin D concentrations were less likely to attain SVR. Our data do not support a role for vitamin D supplementation as an adjuvant therapy for HCV.