Shorter AZT Treatment Reduces Mother to Child HIV Transmission as Well as Longer Treatment but for Less Cost

A shorter course of AZT therapy than currently prescribed for HIV-infected pregnant women may allow women in developing countries to afford the treatment that can reduce their babies' chances of contracting AIDS, but at a much lower cost, according to a study in the October 5 New England Journal of Medicine.

The study, conducted by researchers from Thailand, France, and the United States, showed that transmission of HIV from a mother to her child can be reduced with shorter treatments of the drug AZT (zidovudine) at 1/5 the usual cost (in U.S. dollars). The study was funded by the National Institute of Child Health and Human Development (NICHD) and the Fogarty International Center, both of the National Institutes of Health.

"This is a large step forward in reducing pediatric AIDS," said Duane Alexander, M.D., Director of the NICHD. "The less-expensive alternative could provide millions of women with treatment that could spare thousands of babies from being infected with the AIDS virus."

Of the more than 1,500 infants that get HIV from their infected mothers every day, 95 percent live in developing countries where the poverty level is high. Many mothers in these regions do not have access to the three-to-six month AZT treatment, now considered the standard treatment to prevent perinatal HIV transmission in developed countries, that would reduce the chance of their babies contracting HIV. This study, the largest of its kind to date, suggests an effective AZT treatment option for HIV-infected mothers that successfully reduces transmission to the child, at significantly lower cost.

"These new strategies to reduce pediatric AIDS can be applied in developing countries with success rates equal to those treatments used in industrialized nations," said Dr. Marc Lallemant, a researcher from the Institut de Recherche pour le Développement, who conducted the study with Thai colleagues.

Studies done in the early 1990s showed that AZT effectively reduced the spread of HIV from mother to child, when given to the mother from the second trimester of pregnancy until delivery, during labor and delivery, and to the baby for six weeks after birth. The average cost of this standard treatment is around $1000 US. In the Thailand study, scientists compared the effectiveness of an AZT control treatment starting at the 28th week of pregnancy and given to the infant for six weeks (called long/long in this research) with AZT treatment regimens that were shorter for the mother (starting at the 35th week of pregnancy, called short/long), shorter for the baby (3 days AZT to the baby called long/short), or shorter for both mother and baby (short/short). The long/long treatment was similar to the standard treatment used in developed countries.

Nearly 1,500 pregnant women from 27 different hospitals in Thailand agreed to join the randomized, double-blind study from 1997 to 1999. In 1998, at the urging of an independent committee that was monitoring the study, researchers dropped the short/short group because the HIV transmission rate was more than double that of the standard long/long AZT treatment group.

The study results showed that the long/short group (mothers treated from 28 weeks pregnant until labor/babies treated for just three days after birth) had a transmission rate of 4.7 percent (and) with an average treatment cost of $200 US. This transmission rate was similar to that observed in the control long/long AZT group, 6.5 percent. These two rates are not significantly different. The standard treatment on which the long/long regimen was modeled costs approximately $1000 US.

Further analysis indicated the importance of mothers receiving the longer treatment, with 1.8 percent of infants whose mothers received the longer treatment already infected with HIV at birth, while 5.1 percent of infants whose mothers got the shorter treatment were infected at birth.

Based on these findings, the researchers recommend that treatment for HIV-infected mothers start at the 28th week of pregnancy and continue until labor. In these cases, the child can be treated for three days after birth, at 1/5 the usual cost. If treatment cannot begin until later in the pregnancy, the researchers suggest treating the infant for a longer time, the full six weeks used in the control treatment.

Even the standard AZT treatment does not completely prevent mother to child HIV transmission. However, the results of this study bring hope that with the cheaper and simpler treatment option, greater numbers of children in the developing world will be born free from HIV infection.

Scientists and physicians who were involved in this study include representatives from the Ministry of Public Health of Thailand; the Institut de Recherche pour le Développement and the Institut National d'Etudes Démographiques, France; Chiang Mai and Mahidol Universities (Thailand) and Harvard University and the University of Massachusetts.


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