The coverage and frequency of data collected to monitor childhood stunting and overweight are often a problem that limits the ability of countries to achieve their desired progress toward meeting their nutrition targets. Data collected for the European region over the last 30 years not only suffers from low coverage and frequency, but much of the data also only spans part of the 0-59 month interval. Saraswati and colleagues envisioned a plan to use statistical methods to extract useful information from the available longitudinal data for that region. The result of their work is published in the July 2022 issue of The Journal of Nutrition.
Data sparsity was overcome through the use of heteroscedastic penalized longitudinal mixed models to predict region-wide, country-level trends over time. Prevalence estimates were stratified by sex and partial age intervals, which increased the available data from 84 sources and 428 estimates to 99 sources and 1786 estimates.
The resulting patterns suggest a generally decreasing trend in stunting as well as a stable, but slightly diminishing rate of overweight. The trends were quite different between low- and middle-income countries, and high-income countries, but no differences were found between age groups or sexes. The authors concluded that the statistical methods used for this work provides useful and robust data on child malnutrition trends over time.
In an editorial, Finaret describes two main contributions of the work by Saraswati and colleagues. The first is linking of datasets that had previously not been done, and the second is the use of a semiparametric mixed-effects approach that recognizes observations are not independent and does not overfit the model. Finaret suggests researchers will need to determine when the approaches can be used or when data are simply too sparse for the approach to work effectively.
Chitra M Saraswati, Elaine Borghi, João J R da Silva Breda, Monica C Flores-Urrutia, Julianne Williams, Chika Hayashi, Edward A Frongillo, Alexander C McLain, Estimating Childhood Stunting and Overweight Trends in the European Region from Sparse Longitudinal Data, The Journal of Nutrition, Volume 152, Issue 7, July 2022, Pages 1773–1782, https://doi.org/10.1093/jn/nxac072.
Amelia B Finaret, Advancing Nutritional Epidemiology by Linking Datasets and Addressing Data Quality, The Journal of Nutrition, Volume 152, Issue 7, July 2022, Pages 1595–1596, https://doi.org/10.1093/jn/nxac092.
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