Evaluating the Role of School-Based Weekly Iron-Folic Acid Supplementation in Shaping Common Morbidity and Growth Outcomes Among Adolescent Girls: Evidence From a Cluster-Randomized Controlled Trial in Central Ethiopia Region.

Nutritional deficiencies and parasitic infections continue to undermine immune defenses and drive anemia rates among adolescents, creating a significant public health challenge in sub-Saharan Africa. Although multiple factors contribute to this burden, the prevention and treatment of iron deficiency (ID) remain the most critical levers for progress. The longer-term effects of weekly iron-folic acid supplementation (WIFAS) on morbidity symptoms and growth outcomes remain unclear. A cluster randomized controlled trial was implemented within a school setting involving a cohort of 306 adolescent girls, divided equally (153) between an intervention and a control arm. Within each district, six schools (five primary and 1 secondary) were randomly selected as clusters, totaling 12 clusters/schools out of 37 schools. In this study, the term clusters pertains to schools. Incidences of morbidity symptoms such as diarrhea, cough, and fever were documented via every 14-day recall symptom log-books over the 6-month observation period. To see the effect, we used generalized estimating equations (GEE) employing a Poisson model with a log link function and a linear mixed-effects model. This trial demonstrated that WIFAS at week 18, the intervention group, showed a 44% reduction in the incidence of morbidity symptoms compared to the control group (IRR = 0.56; 95% CI: 0.32-0.99; p = 0.045. This reduction effect was sustained at later time points, with significant reductions observed at week 20 (IRR = 0.52, 95% CI: 0.31-0.89, p = 0.018) and week 24 (IRR = 0.54, 95% CI: 0.32-0.91, p = 0.019). However, there was no association between WIFAS and weight (β = 0.008; 95% CI: -0.13, 0.14) and BAZ score (β = 0.02; 95% CI: -0.2, 0.25) change (p > 0.05). This trial indicates that the reduction effect of WIFAS on morbidity symptoms is not immediate but emerges after 4 months of consistent intake. While the initial effect at week 18 reached the threshold for statistical significance, the sustained reduction through weeks 20 and 24 suggests that prolonged supplementation is necessary to reduce common illnesses. This delay likely reflects the time required to replenish iron stores and enhance immunity. However, the lack of significant effects on weight and BAZ indicates that 6 months of supplementation may be too short a duration to elicit anthropometric improvements.

trial registrationPACTR202309541331083 Registered 12 Sep 2023.