Demographic determinants of hepatitis C virus seroprevalence among blood donors.

Objective.-To measure demographic determinants of hepatitis C virus (HCV) seroprevalence among blood donors in the United States. Design.-Cross-sectional epidemiological study. Setting.-Five blood centers in different regions of the United States. Subjects.-A total of 862 398 consecutive volunteer blood donors with one or more nonautologous donations from March 1992 through December 1993. Methods.-Demographic data collection, serological screening with second-generation anti-HCV enzyme immunoassay, and confirmation with anti-HCV recombinant immunoblot. Results.-There were 3126 donors with at least one blood donation confirmed HCV-seropositive, for a crude prevalence of 3.6 per 1000. Age-specific HCV seroprevalence rose from 0.5 per 1000 in donors younger than 20 years to a maximum of 6.9 per 1000 in donors aged 30 to 39 years and declined in older age groups. There was interaction between age and educational attainment, with 30- to 49-year-olds with less than a high school diploma at highest risk of HCV infection (odds ratio [OR], 33.0; 95% confidence interval [CI], 23.0 to 47.2 compared with those younger than 30 years with a bachelor's degree or higher degree), Other independent risk factors for HCV seropositivity included male sex (OR, 1.9, 95% CI, 1.8 to 2.1), black race (OR, 1.7, 95% CI, 1.6 to 1.9), Hispanic ethnicity (OR, 1.3, 95% CI, 1.1 to 1.5), previous blood transfusion (OR, 2.8; 95% CI, 2.5 to 3.1), and first/only time donor status (OR, 4.2; 95% CI, 3.9 to 4.5, compared with repeat donors), Seropositivity for human T-lymphotropic virus types I and II, human immunodeficiency virus, or hepatitis B core antigen was highly associated with HCV seropositivity (OR, 10.4; 95% CI, 9.6 to 11.4 for one vs no marker). Conclusions.-Despite a low overall HCV prevalence in blood donors in the United States, there is marked variation in HCV seroprevalence by demographic subgroup, even after controlling for prior blood transfusion, a recognized risk factor for HCV. Further study of the prevalence of other parenteral risk factors such as past injection drug use among blood donors is needed.