Anonymous HIV Testing With Participant-Controlled Access to Results Using Handheld Computers: A New Model of HIV Testing Used in a Household Survey in Rural South Africa

Abstract

ANONYMOUS HUMAN IMMUNODEFICIENCY VIRUS (HIV) surveys aim to provide unbiased estimates of HIV prevalence and are essential for monitoring the burden of HIV in a population. However, anonymous HIV surveys allow only limited linkage with risk factor data and do not allow participants to be informed of their HIV results.1 This is an important disadvantage in the face of evidence of individual and public health benefits of knowing one’s HIV status and the increasing availability of antiretroviral therapy worldwide.2–4 In accordance with ethical guidelines,5–7 anonymous HIV surveys usually refer participants to voluntary counseling and testing (VCT) services where these exist or else set up parallel VCT systems.8,9 This means that participants who wish to know their HIV status need to be bled and tested twice. Acceptance rates for such repeat VCT are not known. The World Health Organization (WHO) has recently called for initiatives to increase access to innovative, ethical, and practical models of HIV testing and counseling.10 We devised a novel approach to anonymous HIV testing which used handheld computer and encryption technology to allow participants in an HIV sero-survey to confidentially access their results. We describe this system of ‘Linked Anonymous Testing with Participant-controlled Results’ (LATPCR) and its operational use in a very large household HIV survey in rural South Africa. The Africa Centre Demographic Information System in the rural district of Umkhanyakude, kwaZulu-Natal, South Africa, has been collecting demographic data from approximately 12,000 households since 2000.11 Fieldworkers visit every household in a circumscribed study area of 435 km2 twice yearly to update sociodemographic and HIV risk factor data on the total resident population of 86,000 Zulu-speaking people (in June 2003). Approximately 60% of the population live in scattered homesteads in deep rural areas with a population density below 400 people per square kilometer.11 This is an area of very high HIV prevalence with rates of 38% reported amongst antenatal clinic attendees.12 Antiretroviral treatment (ART) was not available in the public sector in South Africa until October 2004. By December 2004, 56 patients were receiving ART in district health facilities (personal communication, Graham Cooke, Africa Centre for Health and Population Studies, 15 May 2007). The HIV survey took place between June 2003 and December 2004 and has been described in detail elsewhere.13 Ethical approval was obtained from the research ethics committee of the Nelson Mandela School of Medicine, Durban. In addition to the routine collection of demographic data, fieldworkers visiting households also approached every adult male (15–54 years) and female (15–49 years) resident in the study area for HIV testing. Written, informed consent was obtained for HIV testing. Eligible participants received detailed verbal and written pretest information. This included information on what an HIV test is, the implications of a positive result, benefits and disadvantages of knowing one’s HIV status, and strategies to reduce risk. It was explained that participants who wanted to could confidentially obtain their HIV results by presenting a unique code at any of the 19 community-based counseling centers. Counseling centers were offices set up for this purpose throughout the study area in community venues such as shops. Lay counselors staffing these centers were also trained to provide health education, weight, and blood pressure checks.14 HIV tests were done on finger-prick dried blood spot samples in accordance with UNAIDS/WHO guidelines.15 HIV serology was determined by antibody testing with a broad based HIV-1/HIV-2 enzyme-linked immunosorbent assay (Vironostika, Organon Teknika, Boxtel, Netherlands) followed by a confirmatory enzyme-linked immunosorbent assay (GAC-ELISA, Abbott, Abbott Park, IL). Samples were collected from the field every 1 to 2 days and transported to the Wellcome Trust Africa Centre laboratory at the Nelson Mandela School of Medicine in Durban, 250 km away. Each individual in the study area was assigned an alphanumeric identification number (ID), linked to his name, sex, and date of birth (Fig. 1). A separate, highly protected data table linked each individual’s ID to a pseudo-ID. Each individual’s pseudo-ID replaced his ID in the study database and could not be linked back to any identifying data except by the senior data manager. This process of ‘pseudonymization’ or ‘reversible anonymization’ always maps a given ID with the same pseudo-ID, thereby protecting participants’ identities whilst linking data from the same person irrespective of the collection time and place.16 The need to retain some linkage with individual identifiers is unavoidable in longitudinal studies where it is necessary to verify a participant’s identity at each contact.Fig. 1: Reversible anonymization of individual data in the ACDIS database.We used public-private key