By Ashlie Chandler

About 162 million children worldwide under age 5 are considered too short for their age, a growth failure called stunting. Despite efforts to improve child growth, stunting has been difficult to prevent and treat, negatively impacting child health and development.

Researchers from the University of Washington School of Public Health studied what causes child stunting and developed a framework to help deliver effective interventions in low-resource settings.

In an article published online in Paediatrics and International Child Health, researchers suggest that infectious diseases may contribute to a larger portion of the stunting burden than previously thought. However, better statistical tools are necessary to understand diseases with multiple causes such as stunting.

“Child stunting is often cited as an underlying cause of lifelong poor health outcomes,” said Emily Mosites, lead author of the study and graduate of the School’s Department of Epidemiology. “That means we need to recognize what is driving stunting in the first place.”

Stunting is defined as being at a height that is more than two standard deviations below the median of a reference population of the same age and sex. In 2012, the World Health Organization (WHO) set a global goal to decrease by 40 percent the number of stunted children by 2025.

“Achieving the WHO milestone for reducing stunting will rely on understanding the contributions of different stunting risk factors in order to design and deliver effective interventions,” the researchers wrote.

To begin to understand these underlying contributions, researchers first evaluated potential causes of child stunting using the Bradford Hill criteria for causation. These are widely accepted guidelines for investigating causality in epidemiological studies.

Five risk factor categories were identified to be the primary child-level causes of stunting, including low birth weight, insufficient diet, environmental enteric dysfunction, infection and toxin exposure.

Researchers then reviewed literature, published between 1970 and 2015, related to these categories. The goal was to calculate a representative population attributable fraction for each risk factor in Africa, Asia and Latin America.

“Given that there are several causes of stunting, it’s possible that stunting in different geographic regions could be a result of a different etiologic make up,” Mosites said.

Researchers estimated that infectious diseases were responsible for large attributable fractions in all settings, and a combination of dietary indicators also comprised a large fraction in Africa. However, this represents only a first step towards mapping out the multiple causes of child stunting.

“Diseases with several causes are complicated,” Mosites said. “If we are hoping to prevent them, we will need to continue improving our tools for modeling complex causality.”

Mosites conducted the research as a PhD student at the School. Elizabeth Dawson-Hahn, Judd Walson, Ali Rowhani-Rahbar and Marian Neuhouser also contributed to the study.