Background: Hepatitis C virus (HCV) testing guidance issued by the Centers for Disease Control and Prevention in 1998 recommends HCV antibody (anti-HCV) testing for persons with specified risk factors. The purpose of this study was to determine the prevalence and predictors of anti-HCV positivity among primary care outpatients and estimate the proportion of unidentified anti-HCV-positive (anti-HCV+) persons using risk-based testing.
Methods: We analyzed electronic medical record data from a 4-site retrospective study. Patients were aged ≥18 years, utilized ≥1 outpatient primary care service(s) between 2005 and 2010, and had no documented evidence of prior HCV diagnosis. Among persons tested for anti-HCV, we fit a multilevel logistic regression model to identify patient-level independent predictors of anti-HCV positivity. We estimated the proportion of unidentified anti-HCV+ persons by using multiple imputation to assign anti-HCV results to untested patients.
Results: We observed 209 076 patients for a median of 5 months (interquartile range, 1-23 months). Among 17 464 (8.4%) patients who were tested for anti-HCV, 6.4% (n=1115) were positive. We identified history of injection drug use (adjusted odds ratio [95% confidence interval], 6.3 [5.2-7.6]), 1945-1965 birth cohort (4.4 [3.8-5.1]), and elevated alanine aminotransferase levels (4.8 [4.2-5.6]) as independently associated with anti-HCV positivity. We estimated that 81.5% (n=4890/6005) of anti-HCV+ patients were unidentified using risk-based testing.
Conclusions: In these outpatient primary care settings, risk-based testing may have missed 4 of 5 newly enrolled patients who are anti-HCV+. Without knowing their status, unidentified anti-HCV+ persons cannot receive further clinical evaluation or antiviral treatment, and are unlikely to benefit from secondary prevention recommendations to limit disease progression and mortality.
Keywords: HCV testing; anti-HCV prevalence; hepatitis C virus (HCV); outpatient primary care; predictors of HCV positivity.
Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.