Billions of dollars for AIDS prevention: Has it all worked?

In January 2003, President George W. Bush asked Congress to support the President's Emergency Plan for AIDS Relief (PEPFAR) with a $ 15 billion pledge to "turn things around" against AIDS ". Congress has agreed, and the program – which has been pursued by the Obama and Trump administrations – has, as stated in the New England Journal of Medicine, "had an unprecedented impact on the HIV and AIDS pandemic".

Do we really know it? Yes, with the exception of a few countries, HIV rates have decreased, but can we say that PEPFAR-funded programs in countries with the highest HIV and AIDS prevalence are responsible for these programs? cuts? After all, infant mortality rates from AIDS have dropped in sub-Saharan countries that have not received funding from PEPFAR.

Unfortunately, PEPFAR did not initially create a statistical plan that could easily answer these questions. A statistical plan is like asking your accountant what data you need to register before starting your business. You will know if you win or lose money. The issue facing PEPFAR was whether they had collected enough data over the years to evaluate their interventions under the program.

These types of after-the-fact badyzes are very difficult. "Obviously, planned badessments are preferable, but we can still learn a lot from post-hoc badessments," says Donna Spiegelman, the new Professor Susan Dwight Bliss of Biostatistics at the Yale School of Public Health. "I would never let the perfect be the enemy of good."

Few people were as qualified as Spiegelman to meet the challenge of knowing if PEPFAR had worked. With a Harvard Ph.D. in Biostatistics and Epidemiology and rigorous training in mathematical statistics, Spiegelman had become an expert in the development of methods of evaluating the science of prevention in public health. In 2014, she was the first (and up to now) biostatistician to receive the National Institutes of Health's Pioneer Award, a kind of MacArthur Engineering Scholarship for biomedical researchers that frees and funds them – $ 500,000 per year for five years – to pursue bold, risky and innovative research.

Around the time Spiegelman received the Pioneer Award, she met Deborah Birx, the recently appointed US AIDS Coordinator and Goodwill Ambbadador. Birx, a physician and former US Army colonel, was director of the HIV / AIDS Division of Centers for Disease Control and Prevention and worked as a physician in Kenya. As Kenya was one of the first recipients of PEPFAR funding, Birx thought it would be a good candidate for Spiegelman; With PhD student Dale Barnhart, Spiegelman focuses on the 10,000 dispensaries of what is called PMTCT – prevention of mother-to-child transmission – of AIDS. PEPFAR has committed $ 248 million to support PMTCT in Kenya between 2004 and 2014, and infant mortality among children under five has halved over this period. "The basic idea," says Spiegelman, "was to see if infant mortality decreased as funding increased."

The reason for the intervention is that, to prevent HIV transmission to children, pregnant women must be tested. "If they are tested," says Spiegelman, "they can be treated – and this treatment will drastically lower the rate of transmission from 30 or 40% to less than 1%."

That was the basic idea, but unraveling causal inferences was anything but simple. Fortunately, as PEPFAR is a US government program, it must report to Congress what it spends each quarter. From these data, Barnhart extracted a decade of PMTCT expenditures. They then obtained data on neonatal and infant mortality from the Kenyan government and other agencies.

Using a "difference of difference" badysis, they were able to examine the effects of varying levels of PMTCT funding among Kenyan provinces. , as well as trends in local infant mortality, and then compare them to other provinces with similar demographic characteristics that did not have PMTCT programs – or had them but with less financial support. The team performed a wide range of sensitivity badyzes to model the missing data, but these had little impact on the results.

"The results were quite spectacular," says Spiegelman. Provinces in the top quartile of PEPFAR expenditures during the study period experienced infant mortality that was more than 30% lower than that observed in the bottom quartile. "The cumulative spending on PMTCT has dramatically reduced child mortality, saving the lives of many Kenyan children," she says. "We have shown, and rigorously, that US investment in PEPFAR has kept its promises."

All of this research was conducted while Spiegelman was a professor of epidemiological methods in the departments of epidemiology, biostatistics, nutrition, and global health. at the Harvard TH Chan School of Public Health. Since July 1st, she has been Director of the new Center for Implementation and Prevention Methods (CMIPS) at the School of Public Health at Yale University. "We hope to be the favorite place for scientific methods of implementation and prevention in the world, it's my dream job."

Source: American Statistical Association