The number of people with hepatitis C in the United States is likely higher than previously estimated. Past estimates were based on extrapolations from a sample population that did not include groups with a higher than average risk for hepatitis C, that is, those who are hospitalized, incarcerated, or homeless.
Hepatitis C, the most common blood-borne virus in the U.S. is now curable, and has been making headlines recently. With interesting presentations at the 2015 Liver Meeting of the American Association for the Study of Liver Diseases (AASLD), new hep C drugs on the horizon, the strengthening of AASLD’s HCV Guidelines, and the forcible stand on hepatitis C treatment taken by the Centers for Medicare and Medicaid, I am giddy with hope. However, a critical article by Brian Edlin and colleagues in November’s Hepatology was a chilly reminder that we have a big problem on our hands.
“Toward a More Accurate Estimate of the Prevalence of Hepatitis C in the United States” is old news to Edlin and other advocates and researchers who have been vocal about the underestimation of the prevalence of hepatitis C in the U.S.. To those who don’t know the back story on this, I’ll begin with a quick summary.
Estimates of the prevalence of chronic hepatitis C infection in the U.S., rely on data gathered from the latest National Health and Nutrition Examination Survey (NHANES). The purpose of the NHANES is to survey the health of the U.S. adult and child population. Using questionnaires, lab tests and physical exams, NHANES tracks diseases, health risks, and the relationship between diet and health.
Participants are selected based on a formula intended to represent the U.S. population of roughly 319 million. There are 5,000 participants in the NHANES. More people live in Truth or Consequences, New Mexico than are enrolled in the NHANES. (Edlin cites 10,000 participants in NHANES.)
However, the sample size of the NHANES is not the problem. The bigger issue is that NHANES is a civilian household survey and does not count people who are in the military, homeless, in temporary housing, incarcerated, hospitalized, or institutionalized. It does not include people who live on Indian reservations or in a U.S. territory such as Puerto Rico. NHANES does not survey those who don’t want to be documented or reveal their HCV status. In short, the NHANES doesn’t include a portion of the population where the hepatitis C prevalence is higher than average.
For years, Edlin and others have been saying that the NHANES data underestimate hepatitis C prevalence. Rather than the 3.6 million people in the U.S, who are hep C-antibody positive and 2.7 million who are infected, Edlin et al. estimate that there are 4.6 million hep C-antibody positive people in the U.S. with 3.5 million infections. This estimate is conservative; Edlin makes the convincing argument that the true prevalence of hepatitis C may be between 5 and 7 million. This higher estimate is supported by others, including research published by Eric Chak and colleagues (“Hepatitis C Virus Infection in USA: An Estimate of True Prevalence,” Liver International September 2011).