Care for hepatitis C is evolving rapidly, with increasingly effective and better-tolerated antiviral therapies being evaluated and approved for use. It’s clear, however, that not everyone who would qualify for therapy has been tested and identified, referred for appropriate care, and offered or given the best therapy available. Furthermore, currently used antiviral drugs—pegylated interferon and ribavirin “base” plus either telaprevir or boceprevir—can cost more than $70,000 for a full course of therapy. It is expected that the new oral antiviral agents will be just as expensive, at least in the short term. All these factors affect personal, medical, public health, and national policy decisions. One fundamental problem in making such decisions is that it’s difficult to estimate the number of people with chronic hepatitis C virus (HCV) infection in the United States who have been identified and have received appropriate care.

Over the past 4 years, members of the Division of Viral Hepatitis at the Centers for Disease Control and Prevention (CDC) have executed and analyzed two large studies of hepatitis C in the United States. Researchers conducting the Chronic Hepatitis Cohort Study (CHeCS) are currently examining records from more than 13,000 patients with hepatitis C (and more than 3500 with hepatitis B) who have been seen at four health care organizations in the United States (in Detroit, Michigan; Danville, Pennsylvania; Portland, Oregon; and Honolulu, Hawaii) since 2006. These patients are drawn from a population of about 1.6 million adults who have received care at these four sites during the approximately 6 years for which retrospective and prospective analysis has been under way. 1, 2 The National Health and Nutrition Examination Survey (NHANES) takes a different approach: random sampling of approximately 5000 non-institutionalized US civilians per year, using standardized household interviews, physical examinations, and testing of serum samples. 3 Details and results of these two studies give a consistent picture of the status of HCV infection in the United States (see flow chart).