Anaemia in Madagascar: selected biochemical determinants and population attributable fraction among women, adolescents, and children–results from a nationally representative cross-sectional survey

Summary Background Anaemia remains a major health concern in Madagascar, yet its determinants have not been systematically quantified. This study aimed to identify selected biochemical determinants for anaemia and calculate population attributable fractions (PAFs) by population group and location. Methods We conducted a nationally representative cross-sectional survey across Madagascar using a two-stage cluster sampling design. Venous blood was analysed for anaemia, malaria, inflammation, and deficiencies in iron, vitamin A, vitamin B12, and folate. Multivariable Poisson regression identified predictors of anaemia, and PAFs were quantified for each determinant. Findings From June 10 to September 7, 2024, we assessed 2168 preschool children (6–59 months), 1543 adolescent boys (10–19 years), 745 pre-menarcheal girls (≥10 years), and 3553 menstruating women (<50 years). Anaemia affected 42.2% of preschool children (n = 787), 31.3% of adolescent boys (n = 496), 29.8% of pre-menarcheal girls (n = 217), and 30.1% of menstruating women (n = 1015). Iron deficiency showed the highest PAF among preschool children and menstruating women (16.8% and 22.9% for any anaemia; 41.4% and 49.2% for moderate/severe), whereas malaria predominated among adolescent boys and pre-menarcheal girls (14.2% and 14.8% for any; 28.4% and 38.8% for moderate/severe). Inflammation and vitamin A deficiency contributed variably, while vitamin B12 and folate deficiencies played negligible roles. Interpretation Iron deficiency was the leading contributor to anaemia among preschool children and menstruating women, whereas malaria predominated among adolescent boys and pre-menarcheal girls. Integrated interventions addressing iron deficiency, malaria, and other infections are essential to reduce the burden in Madagascar. Funding UNICEF, World Food Programme, German Cooperation, World Bank, and US Government.