Global Trends in Malnutrition

Summary of published paper¹

Child with Kwashiorkor in Kalongo, Pader.

A recent study set out to estimate trends in childhood underweight by geographic regions of the world in order to determine whether the UN Millennium Development Goals (MDGs) were on track. The MDGs aim to reduce by half the prevalence of underweight among children younger than 5 years between 1990-2015. The source of data for the study was the World Health Organisation (WHO) global database on child growth and malnutrition which includes data on approximately 31 million children under five years participating in 419 national nutritional surveys in 139 countries from 1965 through to 2002. The work was based on a time series study of prevalence of underweight, defined as: weight 2 standard deviations below the mean weight for age of the NCHS² and WHO reference population. Linear mixed-effects modelling was used to estimate prevalence rates and numbers of underweight children by region in 1990 and 2015 and to calculate the changes to these values between the two years.

Worldwide, underweight prevalence was projected to decline from 26.5% in 1990 to 17.6% in 2015, a change of -34% (95% confidence interval, -43% to -23%). In developed countries, the prevalence was estimated to decrease from 1.6% to 0.9%, a change of -41% (95% CI, -92% to 343%). In developing regions, the prevalence was forecasted to decline from 30.2% to 19.3%, a change of - 36% (95% CI, - 45% to -26%). In Africa, the prevalence of underweight was forecasted to increase from 24% to 26.8%, a change of 12% (95% CI, 8% to 16%). In Asia, the prevalence was estimated to decrease from 35.1% to 18.5%, a change of -47% (95% CI, -58% to -34%). Worldwide, the number of underweight children was projected to decline from 163.8 million in 1990 to 113.4 million in 2015, a change of -31% (95% CI, -40% to - 20%). Numbers are projected to decrease in all subregions except those of sub-Saharan, Eastern, Middle and Western Africa, which are expected to experience substantial increases in the number of underweight children.

A number of limitations to the study are highlighted. These include limited availability of trend data, surveys not always done randomly, variations in data quality and not accounting for uncertainty in each survey's prevalence estimate (an estimate of variance for each prevalence was not included in the regression analysis so confidence intervals are likely to be too narrow)

The authors conclude that an overall improvement in the global situation is anticipated; however neither the world as a whole nor the developing regions, are expected to achieve the MDGs. This is largely due to the deteriorating situation in Africa where all sub-regions except northern Africa, are expected to fail to meet the goals. This deterioration is likely to be partly due to the effect of HIV/AIDS together with the political and social instability in many African countries.

¹De Onis. M et al (2004): Estimates of Global Prevalence of Childhood Underweight in 1990 and 2015. JAMA, June 2nd, 2004, vol 291, No 21, pp 2600-2606.

²National Center for Health Statistics / CDC Atlanta US.