Selective versus universal antenatal HIV testing: epidemiological and implementational factors in policy choice

Objective: To develop an epidemiological basis for economic analyses of sel ective and universal antenatal screening strategies, and to apply it to the UK. Methods: The prevalence of higher-risk women and the prevalence of undiagno sed infection within groups of high-risk and low-risk women was estimated f rom surveillance and survey data. The numbers of women tested and the numbe rs of infected women who would be identified by universal and selective str ategies were then calculated under a range of assumptions about the identif ication of higher-risk women and acceptance of testing. Results: In higher-risk women estimated prevalence of undiagnosed infection was between 0.06% and 2.8%, comparing well with independent estimates. In low-risk women, estimates ranged from 0.014% in London to 0.002% in the res t of the UK. If uptake among the high-risk women was the same in selective and universal strategies, universal testing would entail testing between 71 00 (London) and 50 000 (rest of England) additional women to detect an addi tional case. However, if selective screening identified only 60% of those a t high risk and achieved only 60% acceptance compared with a universal prog ramme, then universal screening would require only 1150 additional women to identify one additional case in London, compared to 6470 in Scotland and 1 3 140 in the rest of the UK. Conclusions: Overall prevalence does not form an adequate basis for determi ning screening strategy. Instead, universal screening can be justified eith er because the prevalence of HIV in the low-risk group is sufficiently high , or because it achieves sufficiently higher uptake relative to selective s creening among those at higher risk. (C) 1999 Lippincott Williams & Wilkins .