Performance of antenatal HIV screening strategies in the United Kingdom.

Background: In 1996 only 13.5% of previously undiagnosed HIV infected women were detected in pregnancy. In this study, all 265 maternity units in the United Kingdom were surveyed to determine the relation between screening strategy, uptake of testing, and detection rate.
Methods: Data on HIV screening strategy and uptake of testing were collected in 1997 by postal questionnaire. The proportion of women with previously undiagnosed HIV infection identified during pregnancy (detection rate) was calculated using data from national obstetric HIV surveillance and unlinked anonymous seroprevalence studies.
Results: 239 (90%) units responded; 25 of these (10%) had a universal offer strategy, 89 (37%) a selective offer, and 125 (52%) tested only women who requested it. All selective units offered testing to injecting drug users, but only 26% to women who had lived abroad in high prevalence areas. Uptake was over 10% in only eight units, all with a universal strategy, and in 76% of selective units it was below 0.1%. The detection rate was 14.7% in universal units, 7.8% in selective units, and 7.7% in on request units. In universal units, detection increased by 6.3% (95% confidence interval 3.7% to 8.8%) for every 10% increase in uptake of testing. There was evidence of both selective presentation for testing and avoidance of testing among infected women.
Conclusions: All current antenatal HIV testing strategies fail to identify most infected women. Universal offer strategies achieve a very low uptake and a poor detection rate. Units with selective strategies tend to test only a minority of women at high risk and do not target all the main high risk groups.