A copula-based geo-additive approach to childhood health outcomes in five West African nations.

Background: Anemia and malnutrition are major contributors to child morbidity and mortality in Sub-Saharan Africa, particularly in West Africa where their prevalence remains high due to multifaceted socio-economic and environmental factors. Malnutrition, as defined by WHO, includes both undernutrition and overnutrition and is linked to increased risk of non-communicable diseases. Anemia, characterized by low hemoglobin levels, impairs oxygen transport and is associated with developmental delays and increased mortality in children. Given their interrelated nature, a joint modeling approach is essential to understand shared risk factors and inform targeted interventions. Methods: This study analyses pooled DHS data from Gabon, Gambia, Liberia, Mauritania, and Nigeria to identify determinants of anemia and malnutrition. Malnutrition is measured using the Composite Index of Anthropometric Failure (CIAF), which integrates stunting, underweight, and wasting for a comprehensive assessment. A copula-based geo-additive joint model is employed to simultaneously examine both conditions, accounting for spatial variation and interdependence. This approach offers a novel framework for informing policy and improving child health outcomes in West Africa. Results: Key predictors of malnutrition and anemia were identified across five West African countries. Malnutrition risk was significantly associated with maternal education, water source, household wealth, child age, gender, and feeding practices. Notably, children from households using non-bottled water sources and those given milk were at higher risk. Several water-source categories were positively associated with malnutrition relative to bottled/sachet water; however, these associations may reflect socioeconomic and residential differences in the reference group and warrant cautious, non-causal interpretation. Anemia risk was significantly lower among urban children and those whose mothers had higher education. Fortified food and egg consumption were protective against anemia, while poverty and poor water sources increased risk. These findings highlight distinct and overlapping determinants of both conditions. Conclusion: This study highlights the complex interplay of socioeconomic, environmental, and dietary factors influencing malnutrition and anemia among children in West Africa. Key predictors include maternal education, household wealth, water source, and feeding practices, with notable geographic variation. Addressing these challenges requires integrated, multisectoral strategies focused on improving maternal education, access to safe water, dietary diversity, and poverty reduction. Geographically targeted interventions and strengthened health systems are essential.