SAN FRANCISCO – Estimates of the number of U.S. residents who have been infected with hepatitis C virus missed about 1.1 million cases, bringing the true total of infections close to 5.2 million, Dr. Brian R. Edlin said at the annual meeting of the American Association for the Study of Liver Diseases.
“The projected burden of disease in the coming decades may be underestimated,” which could skew planning for public health interventions and future health care services, said Dr. Edlin of Cornell University, New York.
Previous estimates used data from the National Health and Nutrition Examination Survey (NHANES), which samples the noninstitutionalized civilian population but excludes several populations at high risk for hepatitis C virus (HCV) infection.
Estimates based on NHANES data from 1988 to 1994 suggested that 3.9 million U.S. residents had HCV antibodies in their blood and 2.7 million were currently infected. NHANES data from 1999 to 2002, which will be published soon, pegged the number of U.S. residents with HCV antibodies at 4.1 million and the number currently infected at 3.2 million, Dr. Edlin said.
He and his associates analyzed other data to estimate the prevalence of HCV antibodies in five groups excluded from NHANES: people who are incarcerated, homeless, hospitalized, in nursing homes, or on active military duty. Data came from the U.S. Census, the Centers for Medicare and Medicaid Services, the Bureau of Justice Statistics, and the published literature. There are no representative samples for any of these five populations, he said.
Data on prisoners in four states suggested that 32% had HCV antibodies. Six studies of homeless populations found HCV antibodies in 22%-53%, for an overall prevalence of 35%. In seven studies of hospitalized patients, the prevalence ranged from 12% to 21%, with 17% overall having HCV antibodies. Nearly 5% of nursing home residents in one small study had HCV antibodies, as did 0.5% of active military personnel in two large studies.
The numbers add up to 1.1 million more people with HCV antibodies on top of estimates based on NHANES data; most are incarcerated or homeless.