HCV Testing Strategies Falling Short in Reach

Newly available, highly effective treatment options have raised awareness of the need to screen for hepatitis C virus (HCV). However, several recent studies indicate HCV testing strategies are falling short both in reaching all positive cases and in retaining positive patients through confirmatory testing, and ultimately medical referral.

Despite national recommendations addressing birth cohort (1945 to 1965) and risk-based HCV screening, it is estimated that more than 50 percent of persons with HCV infection remain unaware of their positive status. Experts say a number of factors contribute to the lack of identification of positive cases including: patients' lack of disclosure of risk factors, non-complete implementation of birth cohort screening, and risk-based screening strategies that miss cases.

Risk-Based Screening Misses Cases
Risk-based testing strategies miss cases of HCV-positive prisoners, according to a study published in the Journal of Urban Health. The authors say a more comprehensive screening model, such as opt-out universal testing, should be considered in higher prevalence populations like in correctional facilities (12 to 34 percent HCV antibody positivity rates among prisoners versus 1.6 percent in the overall U.S. population).

The Federal Bureau of Prisons recommends HCV testing for all self-reported, high-risk inmates. In actual practice, correctional facility screening protocols vary from universal testing to opt-in risk-based testing. But the authors say correctional facilities provide an opportunity for case identification and secondary prevention, among an otherwise difficult-to-reach population.

To assess the size of the potential shortcomings of risk-based screening strategies, Philadelphia Department of Public Health (PDPH) researchers compared the cases identified through standard targeted testing among Philadelphia Prison System (PPS) inmates (from 2011 to 2012) to blinded HCV seroprevalence results of 1,289 prisoners (the PDPH Study Cohort). Targeted HCV testing is conducted either due to HIV-positive status (approximately one to two percent of the prison population) or because of self-reported intravenous drug use. The PDPH Public Health Laboratory tested the remaining blood from compulsory syphilis testing conducted on all prisoners in the PDPH Study Cohort.

Over the study period, PPS processed 51,562 inmates, of which 5.3 percent were identified as high-risk and underwent targeted HCV screening. Of the 2,727 tested, 57 percent were HCV antibody positive, which when extrapolated would suggest a 3 percent anti-HCV positivity rate for the entire PPS population. However, in the PDPH Study Cohort, 12 percent of tested samples were anti-HCV positive. The authors say that since only 5.3 percent of the prison population was tested due to risk, an additional 4,877 HCV-positive inmates are projected to have been missed.

"Having a substantial proportion of HCV-infected patients remain untested while housed in a correctional institution presents a critical missed opportunity," write the authors led by Danica Kuncio, from PDPH. "Opt-out universal HCV screening of all prison entrants would adequately identify these individuals, the first step in meeting a facility's legal obligation to provide quality and equal medical care to institutionalized individuals."

The authors acknowledge a correctional department's choice of a testing strategy is likely influenced by budget constraints and the expected length of stay for each inmate. However, the authors note, confirmatory testing and disease follow-up in a "controlled setting" prevents loss of patients during follow-up.

HCV Testing Strategies Contribute to Follow-Up Loss
In a separate study, PDPH researchers assessed patient loss across stages of the continuum of care (CoC; January 2010 to December 2013) using reportable data from PDPH's Hepatitis Surveillance Program. Reporting is mandated for all positive HCV laboratory results on Philadelphia residents, including HCV antibody, RNA, and genotype results. Using National Health and Nutrition Examination Survey HCV prevalences, census data, and published homeless and incarceration rates, the expected HCV seroprevalence in Philadelphia was estimated to be 2.9 percent.

Positive HCV antibody test results were received for 47 percent of the estimated HCV-positive individuals. Only half of these patients with positive antibody results had a reported RNA result. Given the estimated 15 percent of HCV cases that spontaneously clear infection, the authors say 33 percent of antibody positive patients were not tested for RNA or their positive RNA results went unreported. The average time between the HCV antibody screening and RNA confirmatory test was 51 days before the 2012 birth cohort recommendation and 15 days post- recommendation. The authors cite reflex testing as driving the dramatic drop.

Takeaway: Given that few HCV-infected residents are successfully mobilized from screening through confirmatory testing and into care and treatment, new strategies need to be adopted to improve initial identification of HCV-positive cases and to keep these cases engaged through the CoC.