What Works in Malaria Control?

This is the first blog in a series of two. Read the second here.

After a comprehensive literature review, expert consultations, public calls for proposals, and advisory group meetings, we’ve mostly decided on a short list of cases for the new edition of Millions Saved—a book of case studies that document global health successes at scale. Selected interventions range from helmet laws to universal health coverage programs—but one of the most well-known global health efforts of the last decade, malaria control, hasn’t made our list -- at least not yet (for more on what did make the list, check back here in the coming months). A malaria intervention was also notably missing from the first edition of Millions Saved.

We want to include a malaria case not only because of its disease burden (the WHO estimates that there were 627,000 malaria deaths in 2012), but also because investments in malaria control have been substantial. The Global Fund has cumulatively spent eight billion fighting the disease since 2002, while the President’s Malaria Initiative’s funding for country implementation and support has totaled over three billion since 2005.

But it’s been challenging to find a malaria case that meets our selection criteria to the same standard as case candidates that address other diseases and health system issues.  Here’s how we define the elements of “success” when selecting a case study on a program/policy/intervention/technology: (i) addresses an important public health problem, (ii) can demonstrate attributable impact on health status using experimental or quasi-experimental approaches, (iii) is cost effective and relatively long-duration, and (iv) has been implemented at a significant scale.

A World Bank paper by Demombynes and Trommlerová seems to be the best evidence of impact we can find; their work shows that increases in ownership of insecticide-treated bed nets in malaria endemic areas of Kenya are responsible for as much as 58 percent of the total decline in infant mortality rate and 39 percent of the post-neonatal mortality decline. But because the study uses Demographic and Health Survey data to estimate the impact at a national level, the mechanism for the allocation of insecticide-treated nets and any programmatic aspects to encourage their use are not well documented. It is hard to discern what made Kenya a malaria success story (and what lessons could be applied elsewhere) without this information on program implementation.

We also read about progress in Swaziland, Senegal, Malawi, Madagascar, and elsewhere in the Roll Back Malaria Progress & Impact Series.  These reports use cross-sectional trend data and modeled impact of lives saved by malaria prevention, making it tough to assign attribution. We found other studies that didn’t quite meet our criteria in other ways. For example a study reviewing mass drug administration in China couldn’t isolate the effects of the intervention from other factors like rain fall and increases in GDP.  And a before-and-after assessment in Tanzania established associations but stopped short of isolating the mortality impact of the malaria program. Neither of these studies measured costs at all.  Finally, a program in Mauritius to prevent the reintroduction of malaria isn’t generalizable (due to geography) and we couldn’t find a convincing counter-factual. 

Perhaps we need to consider a different standard for the evaluation of infectious disease prevention and control programs. 

Unlike other health issues, it’s essentially impossible to do a rigorous evaluation when a program’s goal is to eliminate a disease entirely. In these cases, we rely on the elimination and eradication protocols established by WHO.

Yet most malaria control programs do not currently aim for elimination, and while many program inputs are considered efficacious based on small-scale studies, we still need to understand whether the scaled programs made a difference for malaria-related health outcomes, or whether it was weather, housing improvements, or economic growth that explain these changes at the population level. And of course there is still room for learning on delivery strategies – what difference does one or another delivery strategy make for effectiveness and costs of distribution, delivery and utilization of malaria-related products and – most importantly—health impact?

This all leaves us wondering: are we missing something? Are there other examples of scaled up malaria programs that meet our criteria? If so, let us know—or share with us your other thoughts—in the comments.

This is a joint post with Miriam Temin. Miriam is coordinating editor for the new edition of Millions Saved.