Prevalence and Factors Associated with Anaemia Among Sub-Saharan African Adolescents: A Systematic Review and Meta-Analysis of Nutritional, Socio-Demographic, Environmental, and Infectious Factors

Abstract

Background/Objectives: Anaemia is a critical public health challenge in Sub-Saharan Africa (SSA), particularly among adolescents. The objective was to estimate the pooled prevalence of anaemia among adolescents in SSA and synthesise evidence on its nutritional and contextual determinants. Methods: A systematic search of databases including PubMed, CINAHL and Web of Science was conducted for studies published from January 2000 to October 2025. The methodological approach was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled prevalence estimates were computed using random-effects models, and heterogeneity was assessed using the I2 statistic and Cochran’s Q test. Subgroup and meta-regression analyses were performed to explore sources of variation. Determinants were synthesised as pooled odds ratios with 95% confidence intervals. Publication bias was evaluated through funnel plot asymmetry and Egger’s regression test. Results: Forty-eight (n = 48) studies involving 76,596 adolescents met the inclusion criteria. The pooled prevalence of anaemia was 33% (95% CI: 0.28–0.39), with substantial heterogeneity across studies. Factors associated with higher odds of anaemia included low dietary diversity (OR 1.74, 95% CI: 1.10–2.74) and poor iron or micronutrient supplementation adherence or lack of supplementation (OR 1.94, 95% CI: 1.25–3.01). Infection-related exposures (OR 3.03, 95% CI: 1.99–4.61) and environmental determinants (OR 2.23, 95% CI: 1.41–3.55) were also significantly associated with anaemia. Socio-demographic factors associated with anaemia included menstrual factors among girls (OR 2.51, 95% CI: 1.58–3.99), household size (OR 3.32, 95% CI: 1.61–6.85), awareness (OR 1.71, 95% CI: 1.08–2.70), and age group (OR 2.37, 95% CI: 1.47–3.83). Conclusions: Anaemia among adolescents in SSA remains an important public health concern, although the pooled estimates should be interpreted cautiously because of substantial heterogeneity and methodological differences across studies. The findings suggest that adolescent anaemia is associated with multiple nutritional and contextual factors, but more consistent and context-specific research is needed to refine regional estimates and guide interventions.