Annual HCV testing and use of core antigen to reduce costs and increase diagnosis during acute HCV
Simon Collins, HIV i-Base
Routine monitoring for viral hepatitis, at least annually, is recommended for HIV positive people in BHIVA guidelines and this may be improved by use of HCV core antigen testing.
An analysis from the UK-CHIC cohort study reported that 88% of HIV positive people have been tested for HCV, but that annual testing is still not widely incorporated in practice, increasing from 25% in 2004 to 56% in 2011, despite being recommended for all patients. 
On the other hand, an encouraging example of integrating HIV testing in a specialist hepatology service was reported. In a retrospective case note review from Newham Hospital (located in an area with high prevalence of HIV, HBV and HCV) approximately 80% of 596 patients had a documented HIV test result (50% through the hepatology clinic). Although no new cases of HIV were identified, it is notable that the refusal rate was only 1.2% (7/596). 
Several groups reported on their experience from using HCV core antigen test which has been available for about a year and that has advantages of two-hour turnaround and lower cost (~20% compared to PCR), and the potential to help diagnose acute HCV.
Results from a two-part study at the Royal Free Hospital in North London, were presented by Robert Carney. In the first part, core antigen testing was validated against HCV seroconversion panels (n=45; genotypes 1a, 1b, 2 and 3). In the second part, the test was assessed in samples from 30 HIV positive gay men with recently diagnosed with acute HCV, detecting all acute cases.
Overall, sensitivity was 100% and specificity was 97,5% (one false positive was reported). Both positive and negative predictive values were 100%. HCV RNA levels were reliably detected at 1250 IU/mL but not at 625 IU/mL. 
Results from the use of core antigen testing from 2013 at St Georges Hospital in south London were reported from a retrospective case note review of 75 patients tested for HCV. Positive antigen results were detected in 8/75 (10.7%), with one false positive and one equivocal result (both negative on HCV PCR). Four patients had new HCV infection including one acute case, three with known HCV (both antigen and antibody positive) and nine were antigen negative and antibody positive (indicated cleared HCV infection). 
At Brighton, 14 cases of acute HCV were identified by HCV PCR from 111 patients with elevated ALT. Core antigen testing also identified 14 people, with one indeterminate result that did not become positive by either test. The positive and negative predictive values in this cohort were 93% and 98% respectively. Notably, 6/11 had a negative HCV antibody result suggesting an advantage in detecting acute infection. 
Unless stated otherwise, references are to the 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool.
- Thornton A et al. P236, Viral hepatitis testing patterns among HIV-positive individuals in the UK Collaborative HIV Cohort (UKCHIC) study. 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool. Poster abstract P236.
- M Lander M et al. Assessing HIV testing in hepatitis: an audit of HIV testing uptake in a specialist hepatology clinic in an area of high prevalence for hepatitis B and C. 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool. Poster abstract P251.
- Carney R et al. A hepatitis C virus core antigen assay is a cost-effective, sensitive and specific test in the detection of acute hepatitis C in HIV infected subjects. 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool. Oral abstract O22.
- Dwyer E et al. Analysis of hepatitis C antigen testing in an urban sexual health clinic. 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool. Poster abstract P297.
- Cresswell F et al. Hepatitis C antigen testing: a reliable alternative for diagnosing acute hepatitis C infection. 3rd Joint BHIVA/BASHH Conference, 3-6 April 2014, Liverpool. Poster abstract 376.