Predictors of anaemia incidence and remission among adolescents: longitudinal evidence from four low- and middle-income countries.

BACKGROUND

Anaemia remains a major public health challenge among adolescents in low- and middle-income countries (LMICs). However, longitudinal evidence on its incidence and remission during this critical period is limited. Most existing studies assess anaemia cross-sectionally, providing limited insight into its progression or potential reversibility. We aimed to examine the dynamics of anaemia during adolescence, estimating incidence and remission over one year and identifying sociodemographic, behavioural, nutritional, and dietary predictors of these transitions.

METHODS

We used data from the Africa Research, Implementation Science, and Education Network's multi-site prospective cohort in Nouna (Burkina Faso), Harar (Ethiopia), Dar es Salaam (Tanzania), and Pune (India). Baseline assessments were conducted between November 2021 and December 2023, with follow-up approximately 12 months later. The analytical sample included 3656 adolescents aged 10-19 years. Haemoglobin was measured using HemoCue® analysers and classified according to World Health Organization standards. We used Poisson regression models to estimate risk ratios (RR).

RESULTS

Anaemia prevalence was 34.4% at baseline and 32.6% at follow-up. Among 2399 adolescents who were non-anaemic at baseline, 21.2% developed anaemia, whereas 45.6% of 1257 adolescents with anaemia achieved remission. Late adolescence (RR = 0.81; 95% confidence interval (CI) = 0.70-0.95), school attendance (RR = 0.67; 95% CI = 0.57-0.80), and frequent consumption of fruits and vegetables (RR = 0.83; 95% CI = 0.73-0.95) were associated with a lower risk of incident anaemia, whereas stunting (RR = 1.61; 95% CI = 1.33-1.96) increased the risk. Remission from anaemia was more likely among school attendees (RR = 1.49; 95% CI = 1.27-1.76), adolescents living with guardians (RR = 1.19; 95% CI = 1.05-1.35), and those who frequently consumed fruits and vegetables (RR = 1.17; 95% CI = 1.06-1.29), but less likely among adolescents with depressive symptoms (RR = 0.75; 95% CI = 0.61-0.92) and stunting (RR = 0.75; 95% CI = 0.62-0.91).

CONCLUSIONS

Anaemia among adolescents in LMICs is both prevalent and dynamic. Diet quality, school participation, household stability, and mental and physical health are associated with these trajectories. National nutrition and health strategies should explicitly target adolescents, integrating dietary interventions with educational and clinical platforms to accelerate anaemia reduction.