How much paediatric HIV infection could be prevented by antenatal HIV testing?

OBJECTIVE: To estimate the reduction in the number of children infected with HIV that might be achieved by extending the provision of voluntary antenatal HIV testing. This effect would be mediated by increased numbers of women infected with HIV who receive an intervention to reduce the risk of vertical transmission (for example, zidovudine or caesarean section delivery), who use an alternative to breast feeding, or whose pregnancy is terminated. SETTING: London, United Kingdom. METHODS: Relevant data were derived from neonatal seroprevalence studies, obstetric and paediatric reporting schemes, and review of external information. Sensitivity analyses were performed for certain parameters. RESULTS: Of 106,000 births annually in London, an estimated 169 are to women infected with HIV whose infection is not currently recognised before pregnancy. An estimated 28-33 children born to these women will be infected. Precise prediction of the number of paediatric HIV infections that could be prevented is difficult because of uncertainty in certain factors, particularly the uptake of antenatal testing and the efficacy and acceptability of interventions to reduce prenatal or perinatal transmission. If a testing programme detected 70% of infected women, none of whom opted for a termination but all of whom exclusively bottle fed and received an intervention which halved the risk of transmission, about 12-16 (42-46%) paediatric HIV infections would be prevented annually. CONCLUSIONS: The estimated cost of preventing each paediatric infection is high, but this should be seen in the context of the lifetime health and social care costs for a child infected with HIV. The feasibility of selective testing should be considered when formulating policies on antenatal HIV testing. Programmes that are introduced should be audited to obtain better estimates of costs and benefits.

Use of anonymous newborn serosurveys to evaluate antenatal HIV screening programmes.

OBJECTIVE: To evaluate the extent to which antenatal HIV screening programmes identify HIV infected women who go to term. DESIGN: Comparison of results of two surveillance systems. An anonymous neonatal HIV serosurvey was used to estimate the numbers of HIV infected women giving birth; reporting by obstetricians was used to assess the proportion who had been identified. SETTING: Three Thames regions. RESULTS: 729,105 neonatal blood samples were tested, of which 484 were HIV seropositive. Newborn HIV seroprevalence is increasing, at different rates, in inner London, suburban London, and in non-metropolitan districts. During the past four years the proportion of infected women who have been identified before delivery is 16.9%, but less than half of these were diagnosed during pregnancy. In 1993 only five of the 128 (4%) previously undiagnosed infected women delivering babies were identified by antenatal screening. CONCLUSION: Despite increased emphasis on antenatal testing for HIV in areas of higher prevalence the number of undiagnosed women delivering babies continues to increase. Consideration should be given to alternative strategies for offering antenatal HIV testing. Antenatal screening programmes should be monitored continuously by comparing anonymous neonatal seroprevalence with clinical reports from obstetricians.

Pneumocystis carinii pneumonia in vertically acquired HIV infection in the British Isles.

In order to review the clinical course, laboratory findings, and outcome of children with vertically acquired HIV infection and Pneumocystis carinii pneumonia, questionnaires were sent to paediatricians in the British Isles who had reported P carinii pneumonia and HIV infection through the British Paediatric Surveillance Unit (BPSU). Paediatric reports from the BPSU are linked to reports of pregnancies in HIV positive women and laboratory reports. P carinii pneumonia was the most frequently reported AIDS indicator disease at AIDS diagnosis, occurring in 22/56 (40%) children born in the British Isles; in a further two children P carinii pneumonia occurred after another AIDS indicator disease. The median age at P carinii pneumonia diagnosis was 4.1 (1.4-27.3) months and in 48% it occurred with other AIDS indicator diseases. Despite intensive treatment the three month survival was only 38%. The nine children surviving P carinii pneumonia subsequently developed further AIDS indicator diseases, in particular HIV encephalopathy and four have since died. P carinii pneumonia was present at AIDS diagnosis in 65% of children developing AIDS in the first year of life and caused 82% of infant deaths. Most children were not known to be at risk of HIV until they presented with P carinii pneumonia. Children with HIV infection develop P carinii pneumonia at an early age and have a poor outcome. Increased awareness of the condition is required to initiate early treatment. Prevention may be a compelling incentive for screening in pregnancy, but further study is required to quantify the risks and benefits of initiating early P carinii pneumonia prophylaxis as well as the impact this might have on life expectancy.

Vertically transmitted HIV infection in the British Isles.

OBJECTIVE: To describe the epidemiology of vertically acquired HIV infection in the British Isles, the level of underreporting, the vertical transmission rate, and clinical spectrum of paediatric AIDS. DESIGN: Confidential, linked registers based on reporting from obstetricians and paediatricians; anonymous unlinked neonatal HIV serosurveys. SETTING: British Isles. SUBJECTS: Children born to mothers with HIV infection. MAIN OUTCOME MEASURES: Trends in HIV infection and vertical transmission rate. RESULTS: In Scotland and the Irish Republic, where most maternal HIV infection is related to drug misuse, the annual number of reports of children born to infected mothers has fallen since 1989. In England and Wales nearly half of maternal infections have been acquired overseas, and the number of children born to these women, and to women who became infected in Britain, is increasing. In south east England the proportion of live births to women whose infection was identified before delivery was only 17% (50/287), compared with 68% (26/38) in Scotland. The vertical transmission rate was 13.7% (23/168), and 23% of infected children developed AIDS in the first year of life. 41% (38/92) of children born to infected mothers who were ascertained after delivery were breast fed, compared with 5% (12/236) of those ascertained before delivery. CONCLUSIONS: The incidence of vertically transmitted HIV infection is increasing in England and Wales. More extensive antenatal testing would enable infected women to be counselled against breast feeding, which could prevent a substantial proportion of vertical transmission in some areas, and would increase opportunities for early diagnosis and treatment of infected children.

Screening for HIV infection in pregnancy.

Antenatal HIV screening policies throughout the British Isles were surveyed and results linked to data on HIV-infected pregnant women notified through the Royal College of Obstetricians and Gynaecologists. Units offering HIV testing to all pregnant women were compared with those offering it only to women considered to be at risk, and in both situations fewer than 50% of infected women were identified as HIV infected for the first time in antenatal clinics. Based on laboratory reports of HIV infection in women of childbearing age, paediatric reports of children born to HIV positive women and unlinked anonymous neonatal screening programmes, there was evidence of under-recognition of HIV infection in pregnancy, particularly in England and Wales.

Prevalence of maternal HIV-1 infection in Thames regions: results from anonymous unlinked neonatal testing.

To monitor the spread of human immunodeficiency virus (HIV) in the heterosexual population, residues of blood samples collected routinely on absorbent paper for neonatal screening (Guthrie cards) in NE, NW, and SW Thames Regions in England have been tested for antibodies to HIV-1 since June, 1988. 323,369 dried blood spots were analysed to end March, 1991. Prevalence of anti-HIV-1 in newborn babies has remained stable in outer London and non-metropolitan districts whereas prevalence in inner London has increased from 1 in 2000 in the 12 months beginning June, 1988, to 1 in 500 in the first 3 months of 1991. Either exponential or linear growth in the numbers of new seropositives could account for the results. That obstetricians were aware of maternal HIV infection in only 20% of infected pregnancies, indicates the extent to which HIV infection goes unrecognised in the heterosexual community.

Antenatal testing for human immunodeficiency virus. Results from the Royal College of Obstetricians and Gynaecologists' National Study of HIV Infection in Pregnancy.

Current policies on antenatal testing for human immunodeficiency virus (HIV) in the main obstetric units of the United Kingdom and the Republic of Ireland were surveyed by postal questionnaire; 294 of 299 units responded. HIV testing was available at 192 (65%) of the 294 units that responded. 414 HIV-positive pregnancies in 386 women were reported from 74 (25%) units. Most were from Scotland, the four Thames Regions, and Ireland. In 46% of the HIV-positive women the infection was identified by antenatal testing; the remainder had been tested previously and knew that they were infected. The findings support the view that selective antenatal testing should be established in areas where no testing is offered at present and possibly that testing should be offered to all pregnant women in high-prevalence areas.