The Addition of Vitamin D Supplementation to Interferon and Ribavirin in the Treatment of Hepatitis C Virus Infection: A Randomised Double-Blind Placebo-Controlled Pilot Study

Background: Vitamin D is known to be involved in the immune response to hepatitis C virus infection and preliminary data suggests that supplementation may improve response to treatment with interferon and ribavirin.

Methods: The ViaDUCT study was a pilot, multi-centre, randomised, double-blind, placebo-controlled, parallel group clinical trial. Participants with hepatitis C who were planned for treatment were recruited and were randomised to 100,000 units oral vitamin D3 supplementation or placebo each month whilst undergoing treatment with interferon and ribavirin-based regimens. The primary outcome was sustained virologic responseat 12 weeks. Secondary outcomes were to identify the proportion of patients who dropped out and to assess for any increase in treatment-related toxicity. Study analyses were performed by modified intention to treat of the primary outcome which was compared between the two arms using logistic regression.

Results: 72 participants were randomised; 35 to vitamin D and 37 to placebo. The mean age of participants was 42.5 and 41.7 years respectively. The majority of trial participants were male - 25 (71%) in the vitamin D arm and 24 (65%) in the placebo arm. Following treatment, 60 (83%) attended for assessment of sustained virologic response at 12 weeks. Sustained virologic response was achieved in 82.9% (95%CI 67.3-91.9%) in the vitamin D arm and 73.0% (95%CI 57.0-84.6%) in the placebo arm. The odds of sustained virologic response at 12 weeks in the intervention arm was not significantly greater than in the placebo arm (adjusted odds ratio 1.74; 95%CI 0.43-6.97, p= 0.44). Adverse events were in keeping with the expected side effect profile of interferon and ribavirin based regimens.

Conclusion: Vitamin D supplementation did not significantly improve sustained virologic response when added to interferon and ribavirin-based treatment. The apparent effect size observed would require a largertrial to establish any true effect of this adjunctive therapy.
Trial Registration: ClinicalTrials.gov Identifier: NCT02053519, URL: https://clinicaltrials.gov/ct2/show/NCT02053519, East of Scotland Research Ethics committee: 13/ES/0116.

Keywords: Vitamin D, Interferon, Ribavirin, Hepatitis C virus.