Evidence Action Welcomes New Rigorous Meta Analysis Showing Benefits of Mass Deworming for Children

July 11, 2016 (Washington, DC) -- Today, Evidence Action welcomes the release of a new study that shows that mass deworming of children has a significant positive effect on child weight, and is highly cost effective, with a weight gain per dollar 35 times greater than school feeding programs.

This study strongly refutes findings from a previous critique of mass deworming of children in developing countries with high levels of parasitic worms, a Cochrane meta analysis by Taylor-Robinson et al (2015) that questioned the long-standing World Health Organization (WHO) policy supporting mass deworming.

The new research, “Does Mass Deworming Affect Child Nutrition?: Meta-analysis, Cost-Effectiveness, and Statistical Power” was authored by Kevin Croke, Joan Hamory Hicks, Eric Hsu, Michael Kremer, and Edward Miguel.

The authors update the Cochrane Analysis by including omitted studies, as well as extract additional data from existing studies. This updated sample includes twice as many estimates as the original work, using the same guidelines for inclusion.

The authors then find a “substantial” and “highly robust” positive effect on child weight resulting from deworming. The effects are particularly large in areas above 20% prevalence; this is the same threshold at which the WHO currently recommends mass treatment. Croke and his colleagues also note this Cochrane analysis does not have adequate statistical power to draw definitive conclusions.

The statistical power of meta analysis is becoming a very important issue in medical research where a vast majority of meta analyses have been shown to be significantly underpowered.

Grace Hollister, Director of the Deworm the World Initiative at Evidence Action says: “The study by Dr. Croke and his colleagues provides extremely important evidence for the benefits of conducting mass deworming for the 870 million children at risk of parasitic worm infections globally. We believe this study bolsters the strong case for school-based deworming even further, as deworming is shown to increase weight in children by .3kg. To put that into context: This weight gain would, for example, move a 3-year-old girl from the 25th to the 50th percentile for the WHO child growth standards.”

The Cochrane Review was used by critics of mass deworming to cast doubt on the impact of mass deworming. This re-analysis of this Cochrane study, and correcting for errors and omissions, effectively puts this debate to rest. It shows what dozens of other well-designed studies over the last two decades have already demonstrated: when adequately powered, scientific research is conducted on the effects of deworming, the results are unequivocal - deworming works for children. 

“There is no question that every child infected with parasitic worms should be treated - in fact, that is the standard of medical care,” say Jeff Brown, CEO of Evidence Action. “The notion of testing every child and treating only those found to have worms is operationally and financially not feasible. A ‘test and treat’ approach requires lab analysis of a stool sample that is slow and expertise that often is not readily available in the poorest areas where worm burdens are especially high. And it costs 4-10 times more per child to test and treat than the very safe mass deworming treatment. This approach would exclude millions of children who are at greatest risk from necessary treatment. This is a not a choice any government of a high-burden country should make.” 

In India, where Evidence Action supported mass deworming of over 200 million children in  early 2016, the total cost per child was less than $.13 USD in 2015.

This study affirms decades of sound research: Mass deworming has demonstrable impact on the health and well-being of children. It is excellent public policy as the most cost-effective way to reach the greatest number of at-risk children in high-burden countries and recommended by the WHO. Based on this evidence and cost-effectiveness, Evidence Action continues to advocate for and support school-based mass deworming through its Deworm the World Initiative.

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About Evidence Action

Evidence Action, a Washington DC-based organization, scales proven development solutions to benefit millions of people affected by poverty. Evidence Action implements cost-effective interventions whose efficacy is backed by substantial rigorous evidence. It currently runs the Deworm the World Initiative and Dispensers for Safe Water, interventions that benefit a combined 320 million people. Its Beta program evaluates and tests promising interventions targeting poor households for their suitability to scale.

About Deworm the World

  • According to WHO estimates, about 846 million children worldwide require preventive chemotherapy for soil-transmitted helminths.
  • Working with governments on national and large-scale deworming programs in  Kenya, India, Ethiopia, Nigeria, and Vietnam.
  • Deworm the World Initiative partners with governments to support treatment of more than 200 million children in the 2015/2016 school year.
  • Supports the world's largest school-based deworming program in India.

For additional information:

Katrin Verclas, Director of Global Communications

katrin.verclas@evidenceaction.org or  + 1 202 888 9886