Menu
Menu
Menu
Menu
Objective: To determine the operational effectiveness of the South African programme for preventing mother-to-child transmission (PMTCT) of HIV in reducing rates of early transmission of infection. Methods: Participants were mother-infant pairs who participated in the South African PMTCT programme between October 2002 and November 2004. This was a prospective cohort study. Three sites in different provinces were selected to represent differences in socioeconomic status and HIV prevalence. Data on antenatal care and labour ward care were obtained from maternal interviews and from reviews of medical records. A total of 665 mother-infant pairs in which the mother was HIV-positive were recruited and 588 (88.4%) were followed up at 3 or 4 weeks postpartum to determine the HIV status and vital status of the infant. Findings: Rural participants were significantly poorer and their health care was significantly worse. Women of higher socioeconomic status and those who received better counselling were more likely to be treated with nevirapine. Rates of early HIV transmission ranged from 8.6% to 13.7%. Maternal viral load was the only statistically significant risk factor for transmission. After adjusting for maternal viral load and prevalence of low birth weight, the odds of transmission were 1.8 times higher at the rural site. Controlling for having had ≥ 4 antenatal visits and any delivery complication reduced the odds of transmission to 1.5 higher at the rural site. Conclusion: Rates of early transmission of HIV in an operational setting using single-dose nevirapine administered both to mother and child are similar to those obtained in clinical trials. Scaling up access to antiretroviral regimens for women will further reduce transmission to infants.
This was a prospective cohort study of mothers and infants seen at three of the 18 national prevention programme pilot sites in South Africa between October 2002 and November 2004. Women were recruited at the health facility either before delivery or within a few days after delivery; they were visited again at 3 to 4 weeks post-delivery. Three areas (the main towns of Paarl and Rietvlei and the dormitory township of Umlazi) were selected to reflect different socioeconomic regions, rural and urban locations and antenatal prevalence rates of HIV. Paarl, in the Western Cape province, is a relatively well-resourced periurban and rural area with a well-functioning health system and a 2004 antenatal HIV prevalence of 9%.12 Rietvlei, a rural area in the Eastern Cape province, is in one of the poorest parts of South Africa and its antenatal HIV prevalence in 2004 was 28%.12 Umlazi, near the port of Durban in KwaZulu–Natal, is a periurban area with formal and informal housing. The socioeconomic status of residents is similar to that in Paarl but the health systems are weaker and the antenatal HIV prevalence in 2004 was 47%.12 All data were collected by trained field researchers. Mothers were interviewed using semistructured interviews at the time of recruitment and during the follow-up visit at 3 to 4 weeks. Topics covered included the extent of antenatal care received, plans for disclosure of HIV status and basic knowledge of HIV/AIDS and of mother-to-child transmission. Obstetric records were reviewed using a record review capture sheet to obtain data on antenatal and intrapartum risk factors for transmission. All interviews were conducted in the preferred language of the participant (Afrikaans, English, Xhosa or Zulu). Nevirapine was considered to have been taken by the mother according to protocol if it was taken between 2 and 24 hours before delivery; nevirapine was considered to have been administered to infants according to protocol if it was given within 72 hours after birth. A measure of socioeconomic status was devised using principal component factor analysis that included six household assets (presence of refrigerator, radio, television, stove, telephone or mobile phone, car) and a question regarding food security. This produced a weighted average, so items with a greater variability (e.g. television) contribute more to the score than items with a lesser variability (e.g. radio). The counselling index measured whether the following three topics were mentioned by the counsellor, nurse or midwife during the woman’s pregnancy (as recalled by the woman): the risk of mother-to-child transmission and breastfeeding, how women could choose the best method to feed their infant, and whether the advantages and disadvantages of feeding options were discussed and the woman was helped to make a suitable choice. For each topic a score of 1 was allocated if the topic was covered. If a mother recalled that she was simply told to formula-feed or to breastfeed, then the general counselling index for that mother was decreased by 1 point. Thus, scores on the counselling index ranged from –1 to 3. During the home visit at 3 to 4 weeks post-delivery, trained field staff collected blood spots on Guthrie cards from all infants and mothers by means of a heel or finger prick. Following overnight drying, the filter paper was inserted into a self-sealing envelope with desiccant. Blood specimens were couriered to the laboratory for analysis. HIV infection in infants was determined from dried blood spots using an HIV-1 RNA quantitation assay (nucleic acid sequence-based amplification with electro chemiluminescent detection, NucliSens HIV-1 QT) with a lower detection limit of 80 copies of HIV RNA per ml of blood (equivalent to 1600 copies HIV RNA per 50 μL dried blood spot)13 and a qualitative HIV-1 DNA polymerase chain reaction assay (Amplicor HIV-1 Monitor, version 1.5). Infants were defined as infected with HIV-1 if they had a detectable viral load > 10 000 copies/ml or were positive on DNA testing or both. Mothers’ HIV status was determined from their medical records. Women and their infants were recruited prior to or within a few days after delivery and followed until 3 to 4 weeks post-delivery. However, in cases where a mother was recorded as HIV-positive but had no detectable viral load, a repeat enzyme-linked immunosorbent assay was done to check for false positives (Vironostika HIV Uni-form II) followed by Access HIV-1/2 new assay (Bio-Rad). When HIV transmission was calculated, infants born to false-positive mothers were removed from the analysis. Quantitative data were entered into a Microsoft Access database using double data entry at a central site (Medical Research Council, Durban). After validation the database was exported to Stata statistical software, version 8.0, for data management and analysis. Comparisons of variables across sites were carried out using χ² tests for categorical variables and one-way analysis of variance for continuous variables (with the exception of income, which was compared using a Kruskal–Wallis test). No adjustments were made for multiple testing because the comparison between sites was viewed as descriptive rather than inferential. All factors in Tables 1 and and22 were examined as potential risk factors using logistic regression. To explain differences between the sites, variables were retained in the models if they were either at least of marginal significance or played a confounding role – that is, inclusion of the variable had a noticeable effect (> 10% change) – on the between-site odds ratios. a Values are age in years (standard deviation).b Values are number (percentage).c Values are mean log viral load (standard deviation).d Values are median income (interquartile range).e Values are mean score (standard deviation). Higher scores of socioeconomic status denote people who have more assets and food security.f Values are number of weeks (standard deviation).g Values are weight in grams (standard deviation).h Values are number with low birth weight (percentage). a Values are mean number (standard deviation).b Values are numerator (percentage).c Values are mean age in weeks (standard deviation).d Values are mean score (standard deviation). Details of the counselling index are given in the Methods section.e Delivery complications are defined as intrapartum haemorrhage, gestational proteinuric hypertension, eclampsia, cephalopelvic disproportion, poor labour, chorioamnionitis, fever, meconium liquor and fetal distress.f Details of the protocol are given in the Methods section.g Values are mean number of days (standard deviation). Ethical approval was obtained from the University of KwaZulu–Natal and permission was obtained from participating institutions. Signed informed consent was obtained at the time of enrolment into the study. All staff signed a confidentiality agreement. Compensation offered to participants for their time was site-specific and took the form of cash (Umlazi), food vouchers (Paarl) or food parcels (Rietvlei).
N/A
