Hepatitis C: A Scourge of the Baby Boomers?

Abstract & Commentary

By Mary Elina Ferris, MD, Clinical Associate Professor, University of Southern California. Dr. Ferris reports no financial relationship to this field of study.

Synopsis: Survey data suggest more than 4.1 million Americans have antibodies to Hepatitis C, and 3.2 million have chronic infection. Most were born between 1945-1964, with past injection drug use as the strongest risk factor.

Source: Armstrong GL, et al. The Prevalence of Hepatitis C Virus Infection in the United States, 1999 through 2002. Ann Int Med. 2006;144:705-714.

The National Center for Health Statistics conducts periodic surveys of nationally representative statistics on the health of the US population. The most recent series was begun in 1999 and is designed to run continuously; data are released every 2 years. This research analyzed data collected from 1999 through 2002 on 15,079 statistically chosen participants. After initial home interviews, 80% completed computer-administered medical histories and gave blood samples.

Anti-Hepatitis C antibodies (anti-HCV) were found in 1.6%, with 1.3% positive for HCV RNA, indicating chronic infection. Prevalence was higher in men and non-Hispanic black ethnicity. Age differences were apparent with 1% in age 20-29, a peak of 4.3% in those 40 to 49 years, then a decline to 0.9% in persons age 60 years and older. Participants who were born in the United States had a higher prevalence of anti-HCV than those who were not, and prevalence increased with decreasing family income and level of education.

Characteristics most often found in HCV RNA-positive participants 20-59 years old were elevated serum ALT levels (58.7%) and history of injection drug use (48.4%). Of all persons reporting an injection drug history, 83.3% had not used injection drugs for at least 1 year before the survey. For HCV RNA-positive persons 60 years of age and older, 21.1% had received a blood transfusion before 1992 or had an abnormal serum ALT level.

Commentary

This interesting survey reveals some startling associations: the large number of chronic Hepatitis C virus (HCV) infections in the United States are limited to a specific age group, and seem to be associated with use of injection drugs and increased sexual contacts in the baby-boomer generation.

Past studies1 have suggested that the incidence of HCV infection increased substantially in 1960-1970 and peaked in the 1980s. This new information confirms those observations and probes more deeply to explain this pattern. Although it did not include homeless or incarcerated persons, it was able to identify 2 risk factors (past injection drug use and elevated serum ALT) for ages 20-59 that would have led to finding 85% of chronic HCV infections. For age 60 and older, the major risk factor was receiving a blood transfusion before screening for HCV began in 1992.

Based on these extrapolations, the authors estimate that 85% of all chronic HCV infections in the United States could be found by screening persons of any age for injection drug history, high risk sexual practices, blood transfusions before 1992 and elevated serum ALT levels.

Reference

1. Armstrong GL, et al. The past incidence of hepatitis C virus infection: implications for the future burden of chronic liver disease in the United States. Hepatology. 2000;31:777-782.