Prevalence and factors contributing to severe undernutrition in children on antiretroviral therapy (ART) drugs in Ilala District, Tanzania.

Undernutrition remains a persistent challenge for children receiving antiretroviral therapy (ART) in low- and middle-income countries. This study determined the prevalence and determinants of severe undernutrition among HIV-positive children under five receiving ART in Ilala District, Tanzania. Clinical and demographic data were analyzed for 334 children enrolled at Care and Treatment Clinics (2020-2024). Nutritional status was evaluated according to WHO growth standards, and Generalized Additive Models explored non-linear associations between immunological and virological markers and nutritional indices. The prevalence of severe undernutrition was 8.1% for underweight, 17.7% for stunting, and 3.0% for wasting. Key determinants included ART adherence, CD4 count, age, household food insecurity, meal frequency and guardian occupation. Optimal ART adherence was associated with higher height-for-age (β = 1.22) but lower weight-for-age (β = -0.54) and lower weight-for-height (β = -1.81). Consumption of three daily meals was associated with higher weight-for-age (β = 0.26) and higher weight-for-height (β = 0.40). Non-linear immunological and virological thresholds accounted for up to 30.5% of deviance in wasting, offering actionable clinical targets for nutritional interventions. These findings provide novel insights for risk-stratification, indicating that nutritional interventions should be intensified when children's immune markers fall below identified thresholds to improve clinical and nutritional outcomes.