Gastroenterology

Gastroenterology

Volume 131, Issue 2, August 2006, Pages 478-484
Gastroenterology

Clinical–liver, pancreas, and biliary tract
Hepatitis C Virus Genotypes and Viral Concentrations in Participants of a General Population Survey in the United States

https://doi.org/10.1053/j.gastro.2006.06.007Get rights and content

Background & Aims: Estimates of the long-term benefits of antiviral therapies for chronic hepatitis C are influenced by the frequency of characteristics that affect response in the population treated. This study determined hepatitis C virus (HCV) genotypes and RNA titers among HCV-infected persons in the general population of the United States.

Methods: Genotypes were determined from the NS5b region, and HCV RNA was quantified by using Amplicor Monitor (Roche Diagnostic Systems, Inc, Branchburg, NJ) from 275 HCV RNA–positive participants in the Third National Health and Nutrition Examination Survey conducted during 1988 to 1994.

Results: The HCV genotypes identified included 1a (n = 142), 1b (n = 73), 2a (n = 8), 2b (n = 27), 3a (n = 17), 4 (n = 3), and 6 (n = 5). Based on weighted analysis of persons infected with genotypes 1, 2, and 3, genotype 1 predominated in all age groups (75.3%). By racial/ethnic group, genotype 1 was found in 90.9% of non-Hispanic blacks, 69.6% of non-Hispanic whites, and 71.2% of Mexican Americans. After adjusting for age and gender, only non-Hispanic black race/ethnicity was independently associated with genotype 1 infection (adjusted odds ratio 4.9; 95% confidence interval, 1.9–12.8). The overall geometric mean concentration of HCV RNA was 2.1 × 106 IU/mL; concentrations >2 million IU/mL were found in 53.0% overall and 50.3% of persons with genotype 1.

Conclusions: Persons with chronic hepatitis C in the United States who may require treatment in the foreseeable future are predominantly infected with genotype 1, including a disproportionate number of non-Hispanic blacks. These features emphasize the need for improved therapies that reduce or eliminate complications from genotype 1 infections.

Section snippets

Study Population

HCV RNA–positive persons were identified from among HCV antibody (anti-HCV)–positive participants in the Third National Health and Nutrition Examination Survey (NHANES III) conducted during 1988 to 1994.6 This survey used a stratified multistage sampling design to produce a representative sample of the civilian noninstitutionalized population in the 50 states. Information collected from each participant included demographic, socioeconomic, and limited risk factor histories. The design, sampling

Results

Of the 284 HCV RNA–positive samples, 275 had a positive amplicon generated from the NS5b region. When compared by pairwise analysis, the frequency distribution of the evolutionary distances of the NS5b region grouped into 3 nonoverlapping clusters, corresponding to genotypes (or clades), subtypes of genotypes, and individual variants within a subtype (data not shown). Genotype was determined for all 275 specimens; 1a was found in 142 specimens, 1b in 73, 2a in 8, 2b in 27, 3a in 17, 4 in 3, and

Discussion

Despite the changing patterns of HCV transmission during the past 20–30 years in the United States,15 most HCV infections are the same genotype, genotype 1, regardless of the population studied.16, 17, 18, 19, 20, 21 However, there appears to have been a temporal shift in the transmission of the subtypes of genotype 1, as indicated in this study by the predominance of genotype 1a compared with genotype 1b overall, and particularly among younger persons. Several studies from Western Europe where

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