Hepatitis C: challenges and opportunities in the laboratory diagnosis of infection

It is estimated that more than four million people living in the United States are infected with hepatitis C virus (HCV), yet only half of them have been diagnosed with the disease.^1,2 About 20 percent of HCV-infected individuals will develop life-threatening complications, including cirrhosis and liver cancer.^2,3 Liver failure due to HCV infection is the leading cause of liver transplantation in the U.S., resulting in a tremendous cost and utilization burden to an already-stressed healthcare system.

Diagnosing individuals and initiating treatment well in advance of end-stage complications therefore has become a public health imperative. That is particularly true in the current era of curative 12-week oral therapy. Directly acting antiviral medications can now result in a greater than 90 percent cure rate regardless of the genotype.⁴ In 2012, the Centers for Disease Control and Prevention (CDC), and more recently the U.S. Preventive Services Task Force, recommended routine serologic testing for all people born between 1945 and 1965 in addition to those with typical risk factors (non-prescription injection drug use and recipients of blood products before 1992).³ Additionally, a rising incidence among men who have sex with men has necessitated routine screening of these individuals as well, particularly those who are also infected with HIV.⁵

In this brief review, we discuss the current testing algorithms for detecting chronic hepatitis C infection, the limitations of such testing, and the implementation efforts occurring nationwide to identify HCV-infected individuals.

Current screening algorithms and limitations

The current screening algorithm for most academic, hospital, and commercial laboratories involves a third-generation enzyme-linked immunosorbant assay (ELISA) which targets antibodies to multiple viral antigens, including the core and nonstructural (NS) proteins N3, NS4, and NS5.⁶ A positive ELISA was historically confirmed by a recombinant immunoblot assay (RIBA), which also detects antibodies against the N3, NS4, and NS5 proteins. Given the time, labor, and added costs associated with the RIBA confirmatory testing, and more important, the need for an HCV RNA quantitative level to diagnose active HCV infection, that two-step method was discontinued. Only the anti-HCV ELISA is used to detect anti-HCV positive individuals, despite its less than 100 percent specificity.⁷

Screening with antibodies continues to be the preferred method of diagnosing HCV infection. Unfortunately, most microbiology laboratories do not perform reflex quantitative HCV viral loads on reactive anti-HCV results. A two-step process results in delays in the diagnosis of chronic HCV infection and missed opportunities for treatment. In one study conducted by the New York City Department of Public Health, one-third of individuals screened positive by antibody testing did not get a confirmatory HCV viral load.⁸ Such a two-step algorithm requires patients to come back for at least one, if not two visits to determine the treatment course based on the presence of HCV viremia and the associated genotype. At least one large commercial laboratory has begun reflexively testing for HCV RNA in all patients with a positive HCV antibody test.9 The Veterans Affairs Administration has also promoted a national policy regarding reflex testing.10 Incorporating reflex testing into the algorithm can enable patients to have fewer clinic visits, reduce the time to treatment, and save healthcare costs.

Other anti-HCV testing options include point-of-care (POC) diagnostics utilizing fingerstick capillary whole blood or venipuncture-collected whole blood. Those assays have been developed and validated, but remain costly.^7,11

An alternative to reflex HCV RNA testing on anti-HCV positive specimens is testing for specific hepatitis C viral proteins that are only detectable in active infection. Specifically, the HCV core antigen test has been studied as a fast and more inexpensive test to confirm active infection, particularly in low-resource settings.^12,13 Though the sensitivity is not as high as HCV RNA detection, the benefit would be in reducing the number of more costly HCV RNA tests in populations where the overall prevalence of active infection is low.^12,13

Genotype and resistance testing

HCV genotyping remains a key component of the diagnostic algorithm of HCV infection. Specific direct active antivirals have different efficacy with different genotypes. That drug specificity may change as more “pan-genotypic” antivirals become available. In addition, some genotypes have lower genetic barriers to developing resistance than others, and adherence counseling becomes more crucial in patients infected with those genotypes. A number of genotyping methods are used including PCR HCV amplification followed by strip-based reverse hybridization, PCR HCV amplification followed by Sanger sequencing, and real-time PCR.¹²

The role of viral resistance testing in patients who fail antiviral treatment is complicated. There is currently no guidance regarding when to order such tests.

Implementation of screening

Implementation of screening programs to identify HCV-infected individuals in specific cohorts has been an area of recent research. In one New York-based hospital, only 47 percent of eligible patients were routinely offered anti-HCV testing despite the 2013 New York State law mandating the offering of anti-HCV testing to individuals born between 1945 and 1965.¹⁴

Researchers from the same hospital initiated a program utilizing their electronic medical record (EMR) system to create a “pop-up” window reminder to screen individuals from that birth cohort. When the “pop-up” reminder did not result in an increase in screening, the researchers initiated automatic laboratory anti-HCV testing orders for all individuals in the cohort, after confirming from the State that individual consent for routine anti-HCV screening was not needed from patients. The “pop-up” window would no longer remind providers that screening was needed, but rather that the patient had a positive HCV antibody test. Researchers were able to see a significant increase in screening rates after that intervention, from 47.2 percent to 87.9 percent.¹⁴

A similar study conducted at the Cleveland Department of Veterans Affairs Medical Center demonstrated that improving patient-centeredness of the screening process in ambulatory settings in addition to implementing reflex HCV viral loads (including using a locally developed electronic HCV management application) had resulted in a nearly 100 percent completion rate of timely HCV viral RNA testing.¹⁰

At the University of California, Los Angeles, a similar initiative has begun. A hepatitis C antibody testing reminder was added as part of the healthcare maintenance section in the EMR in August 2015. Since August, anti-HCV testing has increased from an estimated coverage in primary care of three percent to 10 percent.

Conclusion

Though screening at-risk groups for HCV infection remains a high national priority, implementation of the recommended screening algorithm has been limited. Targeted interventions, including additions to EMRs, reminders, and standing orders that include reflex HCV RNA testing on anti-HCV positive specimens, can help improve case-identification, initiate early treatment, and ultimately reduce healthcare costs.

References

1. Holmberg SD, Spradling PR, Moorman AC, Denniston MM. Hepatitis C in the United States. N Engl J Med. 2013;368(20):1859-1861.
2. CDC. Viral Hepatitis: Hepatitis C overview and statistics. 2015. http://www.cdc.gov/hepatitis/hcv/hcvfaq.htm – section1. Accessed January 31, 2016.
3. CDC. Recommendations for the identification of chronic hepatitis C virus infection among persons born during 1945-1965. Morbidity and Mortality Weekly Report.2015.
4. IDSA. HCV Guidance: Recommendations for Testing, Managing and Treating Hepatitis C. 2015. http://hcvguidelines.org/. Accessed January 31, 2016.
5. Wilkin T. Clinical Practice. Primary care for men who have sex with men. N Engl J Med. 2015;373(9):854-862.
   Barrera JM, Francis B, Ercilla G, et al. Improved detection of anti-HCV in post-transfusion hepatitis by a third-generation ELISA. Vox Sang. 1995;68(1):15-18.
6. CDC. Testing for HCV infection: an update of guidance for clinicians and laboratorians. Morbidity and Mortality Weekly Report.2013;62.
7. McGibbon E, Bornschlegel K, Balter S. Half a diagnosis: gap in confirming infection among hepatitis C antibody-positive patients. Am J Med.2013;126(8):718-722.
8. LabCorp. Lab Update: Testing for hepatitis C virus. In: LabCorp, editor.; 2012.
9. Hirsch AA, Lawrence RH, Kern E, Falck-Ytter Y, Shumaker DT, Watts B. Implementation and evaluation of a multicomponent quality improvement intervention to improve efficiency of hepatitis C screening and diagnosis. Jt Comm J Qual Patient Saf. 2014;40(8):351-357.
10. Klausner JD, Baghdadi J. An update on diagnostics for hepatitis C. MLO.2015;47(4):34-36.
11. Cloherty G, Talal A, Coller K, et al. The role of serologic and molecular diagnostic assays in the identification and management of hepatitis C virus infection. J Clin Microbiol. 2015;54(2):265-273.
12. Mullhaupt B, Bruggmann P, Bihl F, et al. Modeling the health and economic burden of hepatitis C virus in Switzerland. PLoS One.2015;10(6) e0125214.
13. Shahnazarian V, Karu E, Mehta P. Hepatitis C: improving the quality of screening in a community hospital by implementing an electronic medical record intervention. BMJ Qual Improv Rep.2015;4(1).