The utility of indirect predictors of hepatitis C viremia

Although the majority of injection drug users (IDUs) have been exposed to hepatitis C (HCV), only 60-85% remain chronically viremic and at risk for HCV-induced progressive liver damage or transmitting HCV to others. Access to direct viral testing to establish the presence or absence of viremia is limited due to its expense. This study of 500 current and former IDUs examines the utility of demographic and biochemical features as a means of indirectly predicting HCV viremia.

Retrospective chart and laboratory review.

Overall, 409 (81.8%) were viremic at the time of presentation. HCV viremia did not correlate with the presence of active drug or alcohol use, drug of abuse, duration of drug use, or length of injecting career, but was more common in males and African-Americans. An elevated ALT, found in 36% of patients, was the best biochemical predictor: 95.6% of these patients were viremic. Other predictors of viremia included thrombocytopenia, hypoalbuminemia, elevated GGT, and total bilirubin level, with a stepwise increase in viremia seen as the number of abnormal biochemical predictors increased. The absence of HCV viremia was more difficult to predict. Viremia was found in 66.3% of those lacking all biochemical predictors and even in 43.8% of those in the lowest 10th percentile of ALT.

Although indirect demographic and laboratory parameters may be used to help predict viremia in 40% of HCV-exposed IDUs, they are inadequate substitutes for direct viral testing and instead should be used only as an adjunct to education and referrals in high-risk patients.