title: Hepatitis C virus antibody positivity and predictors among previously undiagnosed adult primary care outpatients: cross-sectional analysis of a multisite retrospective cohort study.
abstract: 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.
authors.affiliation: Division of Viral Hepatitis, Centers for Disease Control and Prevention.
authors.forename: Bryce D
authors.initials: BD
authors.lastname: Smith
authors.affiliation: Centers for Disease Control and Prevention Foundation, Atlanta, Georgia.
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Yartel
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Katherine
authors.initials: K
authors.lastname: Krauskopf
authors.affiliation: University of Alabama at Birmingham.
authors.forename: Omar I
authors.initials: OI
authors.lastname: Massoud
authors.affiliation: Henry Ford Hospital, Detroit, Michigan.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Brown
authors.affiliation: University of Texas at Houston.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Fallon
authors.affiliation: NORC at the University of Chicago, Illinois.
authors.forename: David B
authors.initials: DB
authors.lastname: Rein
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006526:Hepatitis C / Q000453:epidemiology*; D018937:Hepatitis C Antibodies / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011320:Primary Health Care; D012189:Retrospective Studies; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014481:United States / Q000453:epidemiology
chemical_list: D018937:Hepatitis C Antibodies
keywords: HCV testing; anti-HCV prevalence; hepatitis C virus (HCV); outpatient primary care; predictors of HCV positivity