Is Age-Based HCV Screening a Benefit?

Using age as the determining factor when screening for hepatitis is more useful than is measuring for elevated levels of alanine aminotransferase (ALT), an enzyme produced by the liver, say researchers from the CDC in Atlanta, Georgia.

Most people with hepatitis C virus (HCV) infection are aged in their late 40s to late 60s and were likely infected 25 to 45 years ago, the researchers say. Most were infected by tainted blood transfusions or IV drug use, kidney dialysis, or use of blood-clotting products.

Both the CDC and the American Association for the Study of Liver Disease recommend HCV testing for people with elevated ALT levels. The authors of the CDC study say that previous studies suggest that providers are more likely to test patients for HCV based on elevated ALT than on assessment of exposure risk factors. In fact, risk-based testing can identify most HCV infection, but only 58% to 63% of primary care providers ask about patients’ risk factors. And about 20% to 30% of HCV-infected people do not report risk factors, or they do not remember having been exposed to a risk.

However, only about 46% of patients are evaluated for liver function, and the ALT test has drawbacks, the researchers say. These include lack of a standard definition for the upper limit of normal and the need for multiple tests over time.

In 2012, the CDC recommended a onetime HCV test for people born between 1945 and 1965. According to the researchers, patients born during that time belong to a “high-prevalence cohort” of nearly 200 million people who could account for 67% to 76% of adult HCV infections.

Which approach is best able to diagnose the most HCV-infected individuals?

The researchers say targeting via the birth cohort has the potential to identify about 1 million more anti-HCV positive people, compared with the strategy based on an elevated ALT result. The prevalence of anti-HCV within the birth cohort was about 4 times that in the adult population born before 1945 or after 1965. Using the birth year cohort as the basis of anti-HCV testing would identify nearly 77% of anti-HCV cases in the U.S. adult population, compared with 50% identification using the ALT strategy.

In 2007, according to study researchers, HCV infection surpassed HIV as an underlying or contributing cause of mortality and accounted for > 15,000 deaths in the U.S. More than 1 million more are projected to die of complications of untreated HCV, they add. Without testing and treatment, the CDC estimates that 60% of people with HCV infection will develop cirrhosis, or the scarring of the liver found in advanced liver disease. Testing ALT would screen about 60 million fewer people than the birth cohort strategy and could fail to identify about 700,000 to 900,000 individual cases of current HCV infection, the researchers say. Implementing both strategies concurrently, however, would identify 87% of anti-HCV cases.

Source
Smith BD, Yartel AK. Am J Prev Med. 2014;47(3):233-241.
doi: 10.1016/j.amepre.2014.05.011.