Meta-Analysis
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World J Gastroenterol. Sep 21, 2013; 19(35): 5917-5924
Published online Sep 21, 2013. doi: 10.3748/wjg.v19.i35.5917
Association between vitamin D and hepatitis C virus infection: A meta-analysis
Livia Melo Villar, José Antonio Del Campo, Isidora Ranchal, Elisabeth Lampe, Manuel Romero-Gomez
Livia Melo Villar, Elisabeth Lampe, Laboratory of Viral Hepatitis, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, RJ 210360-040, Brazil
José Antonio Del Campo, Isidora Ranchal, Manuel Romero-Gomez, Unit for the Clinical Management of Digestive Diseases and CIBERehd, Hospital Universitario de Valme, 41014 Sevilla, Spain
Author contributions: Villar LM and Romero-Gomez M contributed to the study concept and design; Villar LM, Del Campo JA and Ranchal I performed data extraction, analysis and interpretation of the data; Lampe E and Romero-Gomez M drafted the review; all authors have read and approved the paper.
Supported by Coordination of Improvement of Higher Education Personnel in part
Correspondence to: Livia Melo Villar, PhD, Viral Hepatitis Laboratory, Helio and Peggy Pereira Pavillion, Ground Floor, Room B09, FIOCRUZ Av. Brasil, 4365, Manguinhos, Rio de Janeiro, RJ 210360-040, Brazil. lvillar@ioc.fiocruz.br
Telephone: +55-21-25621918 Fax: +55-21-22706397
Received: December 14, 2012
Revised: January 31, 2013
Accepted: February 9, 2013
Published online: September 21, 2013
Processing time: 281 Days and 4.6 Hours
Abstract

AIM: To evaluate the association between 25-hydroxyvitamin D [25(OH)D] and sustained virological response (SVR) in hepatitis C virus (HCV) infected individuals.

METHODS: Relevant studies were identified by systematically searching MEDLINE databases up to March 2012 and abstracts of the European and American Congress of Hepatology conducted in 2011. Studies must provide information on SVR and the levels of 25(OH)D3 and/or 25(OH)D2 [henceforth referred to as 25(OH)D] in sera samples from HCV infected individuals. The inclusion criteria were: clinical studies that included HCV infected patients aged older than 18 years regardless of HCV genotype or ethnic group; provided information on SVR rates; and were reported in the English language as full papers. Due to the heterogeneity of studies in categorizing serum vitamin D levels, a cut-off value of 30 ng/mL of serum 25(OH)D was used. Heterogeneity was assessed using I2 statistics. The summary odds ratios with their corresponding 95%CI were calculated based on a random-effects model.

RESULTS: Overall, 11 studies (8 observational and 3 interventional) involving 1575 individuals were included and 1117 HCV infected individuals (71%) showed low vitamin D levels. Most of the studies included mono-infected HCV individuals with the mean age ranging from 38 to 56 years. Four studies were conducted in human immunodeficiency virus/HCV infected individuals. Regarding vitamin D measurement, most of the studies employed radioimmunoassays (n = 5) followed by chemiluminescence (n = 4) and just one study employed high performance/pressure liquid chromatography (HPLC). Basal vitamin D levels varied from 17 to 43 ng/mL in the studies selected, and most of the HCV infected individuals had genotype 1 (1068/1575) with mean viral load varying from log 4.5-5.9 UI/mL. With regard to HCV treatment, most of the studies (n = 8) included HCV individuals without previous treatment, where the pooled SVR rate was 46.4%. High rates of SVR were observed in HCV individuals with vitamin D levels above 30 ng/mL (OR = 1.57; 95%CI: 1.12-2.2) and those supplemented with vitamin D (OR = 4.59; 95%CI: 1.67-12.63) regardless of genotype.

CONCLUSION: Our results demonstrated high prevalence of vitamin D deficiency and high SVR in individuals with higher serum vitamin D levels or receiving vitamin D supplementation.

Keywords: Vitamin D; Hepatitis C; Therapy; Meta-analysis; Sustained virological response

Core tip: High vitamin D levels (above 30 ng/mL) or supplementation are associated with sustained virological response in hepatitis C virus infected individuals.