Lamivudine-zidovudine combination for prevention of maternal-infant transmission of HIV-1

Special considerations for the HIV-infected patient with preterm labor

It is essential that women admitted for PTL have a confidential review of maternal history and prenatal record for HIV serostatus. Combination ARV therapy should be continued during tocolysis of PTL and, if tocolysis fails, through delivery. Counseling and rapid HIV testing should be performed in the intrapartum or postnatal periods if the woman's serostatus has not been determined. Women identified as being HIV infected who are in labor should be treated with (1) ZDV in labor and for 6 weeks to the neonate, (2) NVP single dose to the mother in labor and single dose to the neonate, (3) ZDV-3TC in labor and to the neonate for 1 week, or (4) NVP (as above) and the ZDV regimen (as above). Cesarean delivery should be recommended to all women when the most recent viral load is greater than or equal to 1000 copies/mL or is unknown. Those charged with the care of HIV-infected pregnant women should make frequent use of the Public Health Service Website (http://www.aidsinfo.nih.gov), which provides a regularly updated, practical, and thorough guide to management of patients who have HIV.

Prevention of perinatal HIV transmission: a review of novel strategies

Significant progress has been made in preventing transmission of HIV-1 from mother to infant. With combination antiretroviral therapies, transmission rates lower than 2% have been achieved in clinical studies. Abbreviated regimens covering labour and the first few days of neonatal life have shown considerable promise in the developing world. Several questions and challenges remain, however. These include choice of the optimal antiretroviral agent(s) and duration of the regimens, availability of antiretroviral agents in developing countries, long-term safety of antiretrovirals during pregnancy and early neonatal life and the problem of breastfeeding transmission in countries where alternatives to breastfeeding are not available. A wider array of strategies for prevention of mother-to-child transmission of HIV-1 during breastfeeding, including passive and active immunisation, may offer much needed answers to the problem of continued HIV transmission from mother to infant.

Selection of resistance mutations in pregnant women receiving zidovudine and lamivudine to prevent HIV perinatal transmission

Two zidovudine/lamivudine regimens for the prevention of HIV perinatal transmission were studied for the selection of resistance mutations. The M184V mutation was detected one week after delivery in six out of fifty women (12%) who received the regimen prepartum, intrapartum and postpartum, and was no longer present 3 months later. No nucleoside reverse transcriptase inhibitor resistance-associated mutations were detected in 50 women who received zidovudine/lamivudine intrapartum and postpartum only. No association with the risk of perinatal transmission was found.

Lamivudine treatment during pregnancy to prevent perinatal transmission of hepatitis B virus infection

Vertical transmission of hepatitis B virus (HBV) can occur occasionally despite vaccination of the child. This vaccination breakthrough has been associated with high maternal viraemia. We treated eight highly viraemic (HBV-DNA >/= 1.2 x 10(9) geq/mL) mothers with 150 mg of lamivudine daily during the last month of pregnancy. HBV-DNA, hepatitis B surface antigen (HBsAg), anti-HBs and anti-HBc of their offspring were measured at birth and at 3, 6 and 12 months, respectively. Twenty-four children, born to untreated HBsAg-positive mothers with HBV-DNA levels >/=1.2 x 10(9) geq/mL served as historical controls. All children received passive-active immunization at birth and were followed-up for 12 months. In the lamivudine group one of the eight children (12.5%) was still HBsAg and HBV-DNA positive at the age of 12 months. All other children seroconverted to anti-HBs and maintained seroprotection. In three children, HBV-DNA was temporarily detected by polymerase chain reaction. In the untreated historical control group, perinatal transmission occurred in seven of 25 children (28%). In highly viraemic HBsAg-positive mothers, reduction of viraemia by lamivudine therapy in the last month of pregnancy may be an effective and safe measure to reduce the risk of child vaccination breakthrough. This approach should be evaluated in a large controlled trial.

Mother to Child Transmission of HIV

Transmission of HIV from mother to child remains a global priority, despite the fact that highly active antiretroviral therapy has dramatically reduced the number of infants born HIV-infected in the Western world. A significant number of children worldwide continue to become infected with the virus daily. Studies examining several modified therapies during pregnancy and labor have shown a considerable reduction in the transmission rate. Beyond drug therapy, factors such as viral load, maternal disease, cesarean deliveries, and placental infection also play important roles in transmission. Breastfeeding continues to be a large source of transmission to infants in less developed countries. New studies are examining components in breast milk and drug therapy in an attempt to prevent maternal-child transmission.

Prevention of perinatal HIV transmission: current status and future developments in anti-retroviral therapy

Significant progress has been made in the battle against transmission of HIV-1 from mother to infant. Antiretroviral regimens covering the later part of gestation, labour and the first few weeks of neonatal life have shown great efficacy in reducing such transmission. With the advent of combination antiretroviral therapies, transmission rates lower than 2% have been achieved in clinical studies. Elective caesarean delivery has been shown to enhance the benefit of antiretroviral regimens; however, the risks associated with this approach in many resource-poor settings in developing countries limit its role worldwide. Abbreviated antiretroviral regimens covering labour and the first few days of neonatal life have shown considerable promise in the developing world, resulting in 50% reduction in transmission. Several questions and challenges remain, however. Amongst them, choice of the optimal antiretroviral agent(s), evaluation of purely post-exposure neonatal prophylaxis, availability of antiretroviral agents in developing countries, long-term safety of antiretroviral therapy during pregnancy and early neonatal life, and the problem of breastfeeding transmission in the developing world are some issues that need urgent attention.

Exposure to antiretroviral therapy in utero or early life: the health of uninfected children born to HIV-infected women

Concerns have been raised over possible adverse effects of prophylactic antiretroviral therapy (ART) on the fetus and newborn. We analyzed data relating to uninfected children enrolled in the European Collaborative Study and investigated the association between ART exposure, perinatal problems, and major adverse health events later in life. Median length of follow-up was 2.2 (0-15.9) years. Of the 2414 uninfected children, 687 (28%) were exposed to ART in all three periods (antenatal, intrapartum, and neonatal). Of the 1008 infants exposed to ART at any time, 906 (90%) were exposed antenatally, 840 (83%) neonatally, and 750 (74%) both antenatally and neonatally. ART exposure was not significantly associated with pattern or prevalence of congenital abnormalities or low birth weight. In multivariate analysis, prematurity was associated with exposure to combination therapy without a protease inhibitor (PI) (OR = 2.66; 95% CI: 1.52-4.67) and with a PI (OR = 4.14; 95% CI: 2.36-7.23). ART exposure was associated with anemia in early life ( <.001). There was no evidence of an association with clinical manifestations suggestive of mitochondrial abnormalities. The absence of serious adverse events in this large cohort of uninfected children exposed to prophylactic ART in the short to medium term is reassuring.

Prevalence of genotypic drug resistance among a cohort of HIV-infected newborns

A retrospective, blinded study was conducted to examine the prevalence of antiretroviral drug resistance among a cohort of HIV-infected infants born in 1998 and 1999 in New York State. The earliest available HIV-positive specimen was tested. Most samples were from infants younger than 60 days of age. Genotype data were generated for the protease and reverse transcriptase genes of HIV-1 proviral DNA from 91 infected infants. Eleven infants (12.1%) had provirus with mutations associated with drug resistance, with all three classes of antiretroviral drugs represented. Two infants (2.2%) had mutations associated with resistance to two classes of antiretrovirals. Perinatal antiretroviral drug exposure was examined; it was not found to be significantly associated with the presence of resistance mutations. However, for those infants who had perinatal antiretroviral exposure and genotypic evidence of drug resistance to HIV, the mutations that were detected correlated with at least one antiretroviral from the perinatal period. The prevalence of genotypic drug resistance among this infant cohort is comparable with that found among recently infected adults. These results suggest that resistance testing should be strongly considered for perinatally infected infants, at the earliest possible time point, to avoid use of antiretroviral drugs to which the infant has preexisting resistance.

Human immunodeficiency virus and pregnancy

The recent spread of HIV infection into the heterosexual population in the United States, Europe, and Australia, as well as its earlier heterosexual presence in the developing world, has led to increased scientific and clinical attention to the role of HIV infection in pregnancy. In managing a pregnant HIV-positive woman, it is most important to treat the patient as someone who is HIV-positive rather than someone who is pregnant. Withholding antiviral or prophylactic therapies from the mother for fear of harming the child is not justified, because failure to treat the mother increases the fetal risk. The most important parameter to follow is the maternal plasma HIV-RNA level, and the most important treatment issue is to reduce this level because it is directly related to the risk of vertical transmission.

Assisted reproductive technology for men and women infected with human immunodeficiency virus type 1

In 2001, the World Health Organization reported 4.3 million new human immunodeficiency virus (HIV) infections in adults globally, 41% of which were in women. During the year 2000, 27% of newly diagnosed HIV infections in the United States occurred in women. In developed countries, the perception of HIV infection has changed from an acute, lethal infection to a chronic illness; the introduction of highly active antiretroviral therapy has decreased morbidity and mortality, and new drug therapies have dramatically decreased perinatal transmission. In view of these advances, some HIV-infected individuals are considering reproduction. Following the lead of organizations in other developed countries, the American College of Obstetricians and Gynecologists has recently endorsed the use of reproductive technology in HIV-infected patients. Which patients should be offered assisted reproduction and what the optimal methods are of decreasing heterosexual and perinatal HIV transmission must be determined.

The evolving art of caring for pregnant women with HIV infection

Care for the pregnant woman who has human immunodeficiency virus (HIV) is highly complex and constantly evolving. The purpose of this article is to describe the pertinent issues regarding women and HIV during pregnancy, including epidemiology of mother-to-child transmission, the effect of the disease on pregnancy, care issues in the perinatal period, and the issues in women's lives that place them at risk for HIV infection. Antiretroviral therapy offers significant reduction in the rate of mother-to-child transmission, and this is presently the cornerstone of therapy for the pregnant woman with HIV. Careful intrapartum management may also reduce the risk of transmission. Clinical studies of treatment modalities continue to offer new hope to prevent transmission of the virus to the fetus.

Short-course therapy with zidovudine plus lamivudine for prevention of mother-to-child transmission of human immunodeficiency virus type 1 in Thailand

To evaluate the efficacy and safety of short-course therapy with zidovudine plus lamivudine for reduction of perinatal transmission of human immunodeficiency virus type 1 (HIV-1), a single-arm, open-label, prospective, nonrandomized study was conducted. One hundred six treatment-naive pregnant women received zidovudine (300 mg) plus lamivudine (150 mg) twice daily from week 34 of gestation until the onset of labor. During labor, zidovudine and lamivudine were given every 3 h. Neonates received zidovudine syrup for 4 weeks and were bottle fed. The median maternal virus load and CD4+ cell count at weeks 32-34 of gestation were 4.33 log10 copies/mL and 274 cells/mm3, respectively. At delivery, the mothers' mean decrease in virus load was 1.55 log10 copies/mL and the mean increase in CD4+ cell count was 93 cells/mm3, compared with enrollment levels. Three neonates were HIV-1 infected, for a transmission rate of 2.83% (95% confidence interval, 1%-8%). There were no serious adverse events in the mothers. Adverse events noted in neonates were anemia (in 6 neonates), elevated transaminase levels (in 1), and thrombocytopenia (in 3). Short-course therapy with zidovudine plus lamivudine appeared to be safe and effective for prevention of perinatal transmission of HIV-1.

The impact of expected HIV transmission rates on the effectiveness and cost of ruling out HIV infection in infants

OBJECTIVE

To quantify the costs and effectiveness of different strategies for ruling out HIV infection in infants born to HIV-infected mothers in the United States.

METHODS

The authors assessed 4 different testing strategies that incorporated serial HIV DNA polymerase chain reaction (PCR) testing with or without enzyme-linked immunosorbent assay (ELISA) antibody testing. Testing costs, false reassurance rates, and incremental cost-effectiveness ratios were compared for the 4 strategies.

RESULTS

In HIV-exposed infants, HIV DNA PCR testing at birth, 1 month, and 4 months of age results in a false reassurance rate of 21 per million (at a 2% transmission rate). Adding an ELISA test lowers the false reassurance rate to 0.052 per million at a cost of $570,000 per additional case detected; adding another PCR lowers the false reassurance rate to 1.49 per million at a cost of $720,000 per additional case detected compared with the 3-PCR strategy. At a high transmission rate (20%), there would be substantially more erroneously negative results (false reassurance rate is 256 per million with PCR testing at birth, 1 month, and 4 months) and consequently more favorable cost-effectiveness ratios with additional testing: $47,000 per additional case detected by adding 1 ELISA test and $59,000 per additional case detected by adding another PCR test.

CONCLUSIONS

False-negative HIV results after serial testing in exposed infants are rare, and the incremental cost-effectiveness ratios of additional tests are substantial at low transmission rates. However, the false reassurance rate increases considerably with a 3-PCR strategy and additional testing becomes more cost-effective at greater transmission rates; therefore, additional testing may be warranted in infants at greater risk of infection.

Antiretroviral therapy in HIV-infected pregnant women and their infants: current interventions and challenges

Advances in antiretroviral therapy for human immunodeficiency virus (HIV)-infected pregnant women have improved maternal health and successfully reduced perinatal transmission from 25% to less than 5%. Maternal treatment is individualized and based on physical and laboratory evaluations. Three categories of drugs are currently approved for use in HIV disease including: (11 nucleoside and nucleotide reverse transcriptase inhibitors; (2) non-nucleoside reverse transcriptase inhibitors; and (3) protease inhibitors. Treatment decisions during pregnancy are complex and require consideration of the physiologic changes of pregnancy, drug interactions, possible maternal and fetal side effects, and psychosocial issues that influence adherence to the chosen therapy.

Post-operative complications after caesarean section in HIV-infected women

This retrospective study evaluated complications associated with caesarean section in HIV-infected women. For each HIV-positive patient ( n=45) a control group of ten seronegative women ( n=450) was matched for age, number of foetuses, gestational age, indication for caesarean section, status of the membranes and kind of anaesthesia. All women delivered in the same hospital using a uniform protocol. We evaluated the duration of stay in hospital after operation, the need for antibiotics after caesarean section, the incidence of minor postoperative complications (mild anaemia, mild temperature or fever 24 h after surgery, wound haematoma or infection, urinary tract infection, endometritis) and major postoperative complications (severe anaemia, pneumonia, pleural effusion, peritonitis, sepsis, disseminated intravascular coagulation, thromboembolism). Most HIV-positive women (64.5%) had a complicated recovery after surgery. A higher incidence of major and minor postoperative complications were observed in the HIV-positive group than in the control group. There was a statistically significant greater incidence of mild anaemia, mild temperature or fever, urinary tract infection and pneumonia in the HIV-positive group. HIV-positive women with less than 500x10(6) CD4(+) lymphocytest/l had higher post-caesarean section morbidity than HIV-positive women with more than 500x10(6) CD4(+) lymphocytest/l. The median duration of hospital stay was significantly higher in the HIV-positive group (median 7 days) than in the HIV-negative group (median 4 days). The rate of HIV vertical transmission was 8.8%. Higher post-caesarean section morbidity was found in HIV-positive women than in controls. Unfortunately, the HIV-positive women (with low CD4 lymphocytes counts), whose infants theoretically will benefit most from caesarean delivery, are also the women who are most likely to experience post-operative complications.

Options for prevention of HIV transmission from mother to child, with a focus on developing countries

Use of antiretroviral drugs among HIV-infected pregnant women in many developed countries has significantly reduced rates of mother-to-child HIV transmission, demonstrating that this route of transmission is amenable to intervention. Prevention of transmission in developing countries has proved to be more difficult, although recent advances in short-course antiretroviral drug interventions have made it an immediate possibility, rather than a distant hope as it was seen to be in the recent past. Non-antiretroviral drug interventions, including washing of the birth canal with antiseptic solution and micronutrient supplementation, have not been found to be effective at interrupting mother-to-child HIV transmission, but may have other benefits for maternal and child health. An important issue for developing countries is prevention of postnatal HIV transmission through breast feeding. In most developing countries, formula feeding is not a reasonable option, given the higher rates of mortality from diarrheal and respiratory disease associated with avoidance of all breast feeding. A promising new line of research has recently been broached with the findings from a study in South Africa, which demonstrated that exclusive breast feeding is associated with a significant reduction in postnatal transmission of HIV.

Antiretroviral therapy during pregnancy and the risk of an adverse outcome

BACKGROUND

Some studies suggest that combination antiretroviral therapy in pregnant women with human immunodeficiency virus type 1 (HIV-1) infection increases the risk of premature birth and other adverse outcomes of pregnancy.

METHODS

We studied pregnant women with HIV-1 infection who were enrolled in seven clinical studies and delivered their infants from 1990 through 1998. The cohort comprised 2123 women who received antiretroviral therapy during pregnancy (monotherapy in 1590, combination therapy without protease inhibitors in 396, and combination therapy with protease inhibitors in 137) and 1143 women who did not receive antiretroviral therapy.

RESULTS

After standardization for the CD4+ cell count and use or nonuse of tobacco, alcohol, and illicit drugs, the rate of premature delivery (<37 weeks of gestation) was similar among the women who received antiretroviral therapy and those who did not (16 percent and 17 percent, respectively); the rate of low birth weight (<2500 g) was 16 percent among the infants born to both groups; and the rate of very low birth weight (<1500 g) was 2 percent for the group that received antiretroviral therapy and 1 percent for the group that did not. The rates of low Apgar scores (<7) and stillbirth were also similar or the same in the two groups. After adjustment for multiple risk factors, combination antiretroviral therapy was not associated with an increased risk of premature delivery as compared with monotherapy (odds ratio, 1.08; 95 percent confidence interval, 0.71 to 1.62) or delivery of an infant with low birth weight (odds ratio, 1.03; 95 percent confidence interval, 0.64 to 1.63). Seven of the women who received combination therapy with protease inhibitors (5 percent) had infants with very low birth weight, as compared with nine women who received combination therapy without protease inhibitors (2 percent) (adjusted odds ratio, 3.56; 95 percent confidence interval, 1.04 to 12.19).

CONCLUSIONS

As compared with no antiretroviral therapy or monotherapy, combination therapy for HIV-1 infection in pregnant women is not associated with increased rates of premature delivery or with low birth weight, low Apgar scores, or stillbirth in their infants. The association between combination therapy with protease inhibitors and an increased risk of very low birth weight requires confirmation.

Safety of antiretroviral prophylaxis of perinatal transmission for HIV-infected pregnant women and their infants

Worldwide, more than 1600 infants become infected with HIV each day. Almost all infections are a result of mother-to-child transmission of HIV, with most of these infections occurring in resource-poor countries. In developed countries, antiretroviral prophylaxis has dramatically reduced perinatal transmission to <2%. The potential now exists to extend this success to resource-poor countries using effective but shorter and less expensive antiretroviral regimens. With the potential widespread use of antiretroviral therapy for perinatal HIV prevention in resource-limited settings, there will be exposure of increasing numbers of infants to in utero and postpartum antiretroviral drugs for which long-term toxicity data is unknown. This article focuses on a review of what is known about safety of antiretroviral regimens used to interrupt mother-to-child transmission for women and their children.

Antiretroviral prophylaxis of perinatal HIV-1 transmission and the potential impact of antiretroviral resistance

Since 1994, trials of zidovudine, zidovudine and lamivudine, and nevirapine have demonstrated that these antiretroviral drugs can substantially reduce the risk of perinatal HIV-1 transmission. With reductions in drug price, identification of simple, effective antiretroviral regimens to prevent perinatal HIV-1 transmission, and an increasing international commitment to support health care infrastructure, antiretrovirals for both perinatal HIV-1 prevention and HIV-1 treatment will likely become more widely available to HIV-1-infected persons in resource-limited countries. In the United States, widespread antiretroviral usage has been associated with increased antiretroviral drug resistance. This raises concern that drug resistance may reduce the effectiveness of perinatal antiretroviral prophylaxis as well as therapeutic intervention strategies. The purpose of this article is to review what is known about resistance and risk of perinatal HIV transmission, assess the interaction between antiretroviral resistance and the prevention of perinatal HIV-1 transmission, and discuss implications for current global prevention and treatment strategies.

Animal models of anti-HIV drugs exposure during pregnancy: effects on neurobehavioral development

In the last 10 years, zidovudine (AZT) has become the main prophylactic therapy against vertical HIV-1 transmission. AIDS Clinical Trials Group (ACTG) 076 have demonstrated that the administration of AZT to HIV-infected women during their third trimester of pregnancy, trough labor and given orally to babies for 6 weeks, reduced by two-thirds the rate of vertical infection. Although the rapid diffusion of this regimen into clinical practice together with the implementation of HIV counseling and testing practices have dramatically reduced the vertical transmission rate in the US and Western Europe, there is a growing concern on the adverse effects of antiretroviral therapy on the fetus and the newborn. In fact, even though shorter regimen therapies that are less complex and expensive to implement in poor countries have been demonstrated as effective as ACTG 076 regimen, the distribution of the risk of vertical transmission in the developing countries is still very high. Consequently, a large number of unborns will be a candidate to developmental exposure to antiretroviral agents. To date, data on the transplacental mutagenicity, carcinogenicity and mitochondrial dysfunction induced by developmental exposure to AZT have been reported in several animal models. Furthermore, one study reported severe yet few human cases of cardiomyopathy and neurological disease likely associated with mitochondrial dysfunction in uninfected infants of seropositive mothers perinatally exposed to AZT. For all of these reasons, many investigations have been focusing on the assessment of the potential adverse effects of nucleoside reverse transcriptase (RT) inhibitors (NRTI) administration during development. A survey of the main results derived from clinical and animal studies is reported here, focusing on those neurobehavioral studies that have been looking for specific and/or aspecific changes in the nervous system induced by NRTI exposure in utero.

Differences in postpartum morbidity in women who are infected with the human immunodeficiency virus after elective cesarean delivery, emergency cesarean delivery, or vaginal delivery

OBJECTIVE

The aim of this study was to assess the impact of elective cesarean delivery on postpartum morbidity in women who are infected with the human immunodeficiency virus (HIV).

STUDY DESIGN

We performed a retrospective study of 401 women who were infected with HIV who were delivered in a single reference center from 1989 through 1999. Women who had cesarean deliveries (n = 201), of which 109 were elective and 92 were emergency, were compared with a group of women who were delivered vaginally (n = 200), composed of the women who were infected with HIV preceding each cesarean delivery.

RESULTS

One or more serious complications occurred after 12% of emergency cesarean deliveries, after 6.4% of elective cesarean deliveries, and after 4% of vaginal deliveries (P =.04). In a multivariate analysis, which was adjusted for maternal CD4 lymphocyte count and antepartum hemorrhage, the relative risk of any postpartum complication (serious or minor) was increased by 1.85 (range, 1.00-3.39) after elective cesarean delivery and 4.17 (range, 2.32-7.49) after emergency cesarean delivery, compared with vaginal deliveries (P =.0001).

CONCLUSION

Postpartum morbidity in women who are infected with HIV was highest after emergency, rather than elective, cesarean deliveries.

Twenty-four month efficacy of a maternal short-course zidovudine regimen to prevent mother-to-child transmission of HIV-1 in West Africa

OBJECTIVE

To assess the 24 month efficacy of a maternal short-course zidovudine regimen to prevent mother-to-child transmission (MTCT) of HIV-1 in a breastfeeding population in West Africa.

METHODS

Data were pooled from two clinical trials: DITRAME-ANRS049a conducted in Abidjan, Côte d'Ivoire and Bobo-Dioulasso, Burkina-Faso and RETRO-CI, conducted in Abidjan. Between September 1995 and February 1998, consenting HIV-1-seropositive women were randomly assigned to receive zidovudine (300 mg) or placebo: one tablet twice daily from 36-38 weeks' gestation until delivery, then in DITRAME only, for 7 more days. Paediatric HIV-1 infection was defined as a positive HIV-1 polymerase chain reaction, or if aged > or =15 months, a positive HIV-1 serology. Cumulative risks (CR) of infection were estimated using a competing risk approach with weaning as a competing event.

RESULTS

Among 662 live-born children, 641 had at least one HIV-1 test. All but 12 children were breastfed. At 24 months, overall CR of MTCT were 0.225 in the zidovudine and 0.302 in the placebo group, a 26% significant reduction. Among children born to women with CD4 cell counts < 500/ml at enrollment, CR of MTCT were similar, 0.396 in the zidovudine and 0.413 in the placebo group. Among children born to women with CD4 cell counts > or =500/ml, CR of MTCT were 0.091 in the zidovudine and 0.220 in the placebo group, a significant 59% reduction.

CONCLUSION

A maternal short-course zidovudine regimen reduces MTCT of HIV-1 at age 24 months, despite prolonged breastfeeding. However, efficacy was observed only among women with CD4 cell counts > or =500/ml. New interventions should be considered to prevent MTCT, especially for African women with advanced HIV-1 immunodeficiency.

Estimating the efficacy of interventions to prevent mother-to-child transmission of HIV in breast-feeding populations: development of a consensus methodology

Postnatal transmission of HIV through breast milk complicates both the design of effective interventions to prevent mother-to-child transmission of HIV (PMTCT) and their evaluation. Estimated long-term efficacy in five African trials (four with peri-partum antiretrovirals and one with artificial feeding) varied from 25 to 50 per cent. This variation may be due, at least in part, to differences in analytical methodology. To facilitate direct comparison between trials, a methodological consensus approach to the analysis and presentation of the results of PMTCT trials was developed. The initial methodology used and results presented from African trials with available long-term efficacy data were reviewed during a workshop in Bordeaux, France, in September 2000. A consensus approach for evaluating efficacy applicable across PMTCT studies was developed. There are four typical situations defined by duration of follow-up (short versus long), and the available demographic (vital status) and biological data (single versus repeat HIV testing). Efficacy can be assessed from the risk of infection directly or from HIV-free survival by combining infection and death as a single endpoint. Studies should report results in a standardized format including infection, weaning, mortality and loss to follow-up. New statistical methods that account for the unknown date when a child would first test positive for HIV, for weaning as a competing risk for HIV infection, and for increased risk of death among HIV-infected children should be used in analysing data from PMTCT studies with repeat HIV testing. All estimates should be reported with confidence intervals. This standardized methodology that allows direct comparison between studies is now being applied to four randomized clinical trials.

Prevention of perinatal HIV infection

In the 20 years since the first description of the clinical manifestations of HIV infection, more than 32 million people have been infected worldwide. In untreated HIV-infected pregnant women, the risk of maternal-child transmission varies from 16 to 40%. In developed countries, utilizing combinations of available medications and elective cesarean sections, it is possible to lower the transmission rates to less than 2 to 4%. Effective programs use universal screening of pregnant women, perinatal antiretroviral therapy, and, at times, delivery via elective cesarean section. In resource-poor areas, major barriers remain to the control of maternal-child transmission.

Guidelines for the management of HIV infection in pregnant women and the prevention of mother-to-child transmission

AIMS OF THE GUIDELINES: These guidelines, drawn up by a multidisciplinary group of clinicians and lay workers active in the management of pregnant women infected with HIV, aim to give up-to-date information on interventions to reduce the risk of mother to child transmission of the virus. The evidence on the use of interventions to prevent mother to child transmission of HIV has been graded according to the strength of the data as per the definitions of the US Agency for Health Care Policy and Research [1]. Weighted evidence on the use of combination antiretroviral therapy (ART) for the treatment of HIV infection per se is presented in the BHIVA guidelines for adults [2,3]. The highest level evidence (i.e. randomised controlled trials (RCTs) or large, well conducted meta-analyses) is only available for formula feeding, prelabour caesarean section and zidovudine monotherapy. The need to treat mothers for HIV infection has led to the widespread use of ART in pregnancy which in turn results in new questions such as how to deliver when the mother, on therapy, has no detectable plasma viraemia with the most sensitive assays. In addressing many common and/or difficult clinical scenarios in the absence of 'best evidence' the guidelines rely heavily on 'expert opinion'. Recommendations for management are given in the section on clinical scenarios, and summarized in Table 3. An expanded version of these guidelines with an appendix on safety and toxicity data is available on the BHIVA website http://www.bhiva.org. The authors are available to discuss individual cases.