Using Electronic Laboratory Data to Monitor the Hepatitis C Care Cascade in California, 2014-2015

BACKGROUND: Clinicians use nucleic acid testing (NAT) to diagnose current hepatitis C virus (HCV) infection following a positive HCV antibody (anti-HCV) test, to inform HCV treatment decisions, and to monitor treatment response.  NAT results collected through routine surveillance offer an opportunity to monitor steps along the HCV “care cascade,” including diagnostic testing, linkage to care, and treatment.  This analysis uses positive HCV NATs to examine the HCV care cascade in California. 

METHODS: Positive HCV test results electronically reported to the California Department of Public Health (CDPH) from January 1, 2014 – December 31, 2015 were extracted from a statewide chronic HCV registry.  Negative test results were unavailable.  Analysis was limited to persons with a positive anti-HCV test and no record of a prior NAT (qualitative, quantitative, or genotype test) since 1994.  Laboratory values were used as proxies for steps along the HCV care cascade: 1) a positive anti-HCV (screening); 2) any positive NAT (diagnostic testing); and 3) ≥2 positive NATs (linkage to care and/or treatment).  Chi-square tests and multivariate logistic regression were used to assess associations of demographic characteristics with receipt of any positive NAT (versus receipt of a positive anti-HCV only). 

RESULTS: From January 1, 2014 – December 31, 2015, 58,814 individuals had a positive anti-HCV test; 21,772 (37 %) had any positive NAT reported, of whom 7,687 (35%) received ≥2 positive NATs.  Factors associated with a greater likelihood of receiving any positive NAT included being male (<.0001) and incarcerated in a California state prison (<.0001).  In multivariate analysis, of those who were not incarcerated in state prisons, persons aged 50 – 69 were more likely to have received any positive NAT compared to persons under 30 years of age (aOR: 1.5, 95% CI 1.4 – 1.6).  

CONCLUSIONS: One-third of individuals with a positive anti-HCV test received any positive NAT (HCV diagnostic testing), and non-incarcerated young adults were less likely than their older counterparts to receive any positive NAT after a positive anti-HCV test.  This analysis is limited by the exclusion of individuals who received negative diagnostic tests, which are not routinely reported in California.  Electronic reports from one large laboratory that serves all California state prisons may have introduced surveillance bias. However, these results are similar to other analyses in which only half of those with positive anti-HCV received NAT, and suggest a need for improved diagnostic testing among all age groups, including non-incarcerated young adults in California.