Multi-Centre Evaluation of the Determine HIV Combo Assay when Used for Point of Care Testing in a High Risk Clinic-Based Population Damian P. Conway 1 *, Martin Holt 2 , Anna McNulty 3,4 , Deborah L. Couldwell 5,6 , Don E. Smith 4,7 , Stephen C. Davies 8 , Philip Cunningham 9,10 , Phillip Keen 1 , Rebecca Guy 1 on behalf of the Sydney Rapid HIV Test Study 1 The Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia, 2 Centre for Social Research in Health, University of New South Wales, Sydney, New South Wales, Australia, 3 Sydney Sexual Health Centre, Sydney Hospital, Sydney, New South Wales, Australia, 4 School of Public Health and Community Medicine, University of New South Wales, Sydney, New South Wales, Australia, 5 Western Sydney Sexual Health Centre, Western Sydney Local Health District, Sydney, New South Wales, Australia, 6 Sydney Emerging Infections and Biosecurity Institute, University of Sydney, Sydney, New South Wales, Australia, 7 Albion Centre, Surry Hills, Sydney, New South Wales, Australia, 8 North Shore Sexual Health Service, Royal North Shore Hospital, St Leonards, Sydney, New South Wales, Australia, 9 St Vincent’s Centre for Applied Medical Research, University of New South Wales, Sydney, New South Wales, Australia, 10 NSW State Reference Laboratory for HIV, St Vincent’s Hospital, Darlinghurst, Sydney, New South Wales, Australia Abstract Background: Determine HIV Combo (DHC) is the first point of care assay designed to increase sensitivity in early infection by detecting both HIV antibody and antigen. We conducted a large multi-centre evaluation of DHC performance in Sydney sexual health clinics. Methods: We compared DHC performance (overall, by test component and in early infection) with conventional laboratory HIV serology (fourth generation screening immunoassay, supplementary HIV antibody, p24 antigen and Western blot tests) when testing gay and bisexual men attending four clinic sites. Early infection was defined as either acute or recent HIV infection acquired within the last six months. Results: Of 3,190 evaluation specimens, 39 were confirmed as HIV-positive (12 with early infection) and 3,133 were HIV- negative by reference testing. DHC sensitivity was 87.2% overall and 94.4% and 0% for the antibody and antigen components, respectively. Sensitivity in early infection was 66.7% (all DHC antibody reactive) and the DHC antigen component detected none of nine HIV p24 antigen positive specimens. Median HIV RNA was higher in false negative than true positive cases (238,025 vs. 37,591 copies/ml; p = 0.022). Specificity overall was 99.4% with the antigen component contributing to 33% of false positives. Conclusions: The DHC antibody component detected two thirds of those with early infection, while the DHC antigen component did not enhance performance during point of care HIV testing in a high risk clinic-based population. Citation: Conway DP, Holt M, McNulty A, Couldwell DL, Smith DE, et al. (2014) Multi-Centre Evaluation of the Determine HIV Combo Assay when Used for Point of Care Testing in a High Risk Clinic-Based Population. PLoS ONE 9(4): e94062. doi:10.1371/journal.pone.0094062 Editor: William R. Abrams, New York University, United States of America Received November 27, 2013; Accepted March 10, 2014; Published April 8, 2014 Copyright: ß 2014 Conway et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The Sydney Rapid HIV Test Study was supported by funding from the National Health & Medical Research Council STI Program Grant (http://www. nhmrc.gov.au/) and NSW Ministry of Health (http://www.health.nsw.gov.au). DPC was supported by a scholarship from Australian Rotary Health/Sydney CBD Rotary Club (http://www.australianrotaryhealth.org.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: dconway@kirby.unsw.edu.au Introduction People with acute HIV infection contribute disproportionately to HIV transmissions due to their high viral loads [1–2]. Mathematical modelling and phylogenetic analysis estimate that those with acute infection account for 19–50% of sexual HIV transmissions in a range of populations and settings [3–5]. Cohort study data show that risk of HIV transmission correlates with viral load [6] and is higher during acute and early infection compared with established infection [7–8]. Earlier identification of HIV infection and initiation of treatment may have both individual [9– 10] and public health [11–12] benefits. While automated fourth generation HIV immunoassays [13] and pooled HIV nucleic acid testing [14] have enabled identification of those with acute infection prior to development of HIV-specific antibodies, these methods are resource intensive and unsuitable for testing outside laboratories. Rapid HIV testing has expanded access to testing in resource poor settings with limited laboratory infrastructure [15] and in high risk or hard to reach populations in resource rich settings [16]. However, if HIV antibody only rapid tests are the mainstay of testing in these PLOS ONE | www.plosone.org 1 April 2014 | Volume 9 | Issue 4 | e94062