To the Editor:
We thank Pang et al. for their interest in our recently published systematic review and meta-analysis involving 2605 patients which found no association between baseline 25-hydroxyvitamin D level and sustained virologic response (SVR) to interferon-based antiviral therapy in chronic hepatitis C infection [
[1]
]. They are correct to highlight the influence of ethnicity on both vitamin D status and genetic polymorphisms in key proteins involved in vitamin D synthesis. The studies included in our meta-analysis contained only a small number of participants of Asian [[2]
] or African-American [[3]
] ethnicity, leading us to highlight the study’s inability to adjust for ethnicity as one of its limitations.With regards to the recently published meta-analysis by García-Álvarez et al. [
[4]
] evaluating vitamin D status and response to hepatitis C therapy, this study differs from ours in that it includes those with HCV-HIV co-infection. Furthermore, we believe this study has significant methodological issues such as the inclusion of three studies involving the same Italian cohort of approximately 200 patients, and the exclusion of five large studies [2
, 5
, 6
, 7
, 8
] from Europe and Australia involving 1569 patients that were readily identifiable using the stated search strategy. Our concerns about this study have recently been published [[9]
] and the validity of the study’s findings should be viewed with caution.- Kitson M.T.
- Sarrazin C.
- Toniutto P.
- Roberts S.K.
Relationship between vitamin D status and response to HCV therapy.
Hepatology. 2015; https://doi.org/10.1002/hep.27797
Our meta-analysis only evaluates the relationship between baseline vitamin D status and SVR. The impact of vitamin D supplementation on outcomes to interferon-based antiviral therapy, although interesting, is a different clinical question that has not been definitively assessed in prospective, randomized controlled trials. We agree that vitamin D has potential anti-viral, anti-inflammatory, anti-fibrotic and immunomodulatory actions relevant to liver disease, which have been highlighted in a number of pre-clinical studies [
[10]
]. However high quality prospective clinical research studies are needed to support the hypothesis that vitamin D deficiency may be responsible for the worse outcomes in HCV related liver disease.Conflict of interest
The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.
References
- Vitamin D level and sustained virologic response to interferon-based antiviral therapy in chronic hepatitis C: a systematic review and meta-analysis.J Hepatol. 2014; 61: 1247-1252
- Vitamin D status does not predict sustained virologic response or fibrosis stage in chronic hepatitis C genotype 1 infection.J Hepatol. 2013; 58: 467-472
- Vitamin D and the racial difference in the genotype 1 chronic hepatitis C treatment response.Am J Clin Nutr. 2012; 96: 1025-1031
- Relationship of vitamin D status with advanced liver fibrosis and response to hepatitis C virus therapy: a meta-analysis.Hepatology. 2014; 60: 1541-1550
- Low vitamin D serum level is related to severe fibrosis and low responsiveness to interferon-based therapy in genotype 1 chronic hepatitis C.Hepatology. 2010; 51: 1158-1167
- Vitamin D deficiency and a CYP27B1-1260 promoter polymorphism are associated with chronic hepatitis C and poor response to interferon-alfa based therapy.J Hepatol. 2011; 54: 887-893
- A genetic validation study reveals a role of vitamin D metabolism in the response to interferon-alfa-based therapy of chronic hepatitis C.PLoS One. 2012; 7: e40159
- Vitamin D levels vary during antiviral treatment but are unable to predict treatment outcome in HCV genotype 1 infected patients.PLoS One. 2014; 9: e87974
- Relationship between vitamin D status and response to HCV therapy.Hepatology. 2015; https://doi.org/10.1002/hep.27797
- D-livering the message: the importance of vitamin D status in chronic liver disease.J Hepatol. 2012; 57: 897-909
Article info
Publication history
Published online: April 18, 2015
Accepted:
April 8,
2015
Received:
April 6,
2015
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© 2015 European Association for the Study of the Liver. Published by Elsevier B.V.
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