Hepatitis C virus genotypes and viral concentrations in participants of a general population survey in the United States.

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 x 10(6) 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.