Prevalence of undernutrition and environmental factors estimated using the composite index of anthropometric failure among children aged 24-59 months in the Democratic Republic of Congo: a secondary data analysis of the National Nutrition Survey 2023

<title>Abstract</title> <p> <bold>Introduction</bold> : Child undernutrition remains a major public health problem in the Democratic Republic of Congo (DRC). While interventions target the first 1,000 days, the 24–59-month age group, a period of continued vulnerability, is often neglected. The study aimed to identify the social and environmental factors associated with undernutrition, in children aged 24 to 59 months in the DRC. <bold>Method:</bold> This study was a secondary analysis of data from the 2023 National Nutrition Survey in the Democratic Republic of the Congo. We analysed data of 10512 children aged 24-59 months. Undernutrition was assessed based on the Composite Index Anthropometry Failure as calculated from weight, height, and age. Statistical analyses, including Chi-square tests (p&lt;0.2), multivariate logistic regression, stepwise multivariate regression (p&lt;0.05) and marginals effect were performed on STATA 17.0, after weighting the data. For controlling multicollinearity, a variance inflation factor (1.3) was assessed. <bold>Results:</bold> The prevalence of undernutrition was 56.7% (95%CI: 54.7%; 58.8%), with a significant disparity (p &lt; 0.001) between rural (63.7%, 95%CI: 61.5%-65.9%) and urban environments (44.9%, 95%CI [41.4%-48.5%). Stepwise analysis identified several protective factors: urban residency (Aor= 0.65: 95%CI 0.59; 0.71), maternal education like secondary (Aor= 0.75, 95%CI 0.68;0.83) and university (Aor= 0.26, 95%CI 0.16;0.41) level and measles vaccination (Aor= 0.81, 95%CI 0.72;0.91). conversely, the factors associated with undernutrition were boys (Aor= 1.34 95%CI 1.24;1.46), child age above 36months (Aor= 1.20, 95%CI 1.11;1.31), households with &gt;2 children (Aor= 1.24 95%CI 1.14;1.35) and recent diarrhea ( Aor = 1.25, 95%CI 1.11;1.40). Predictive margins confirmed a systematic geographic gap (rural areas remaining consistently more vulnerable). However, a crucial intersection point emerged: a mother's university education reduced rural undernutrition prevalence to approximately 33% (95%CI 22 ;42%), crossing and outperforming the urban setting where children of uneducated mothers displayed a prevalence of 54%. <bold>Conclusion:</bold> Interventions must be extended beyond 24 months and must incorporate hygiene promotion (WASH) and, in the long term, education for girls to ensure a lasting impact. </p>