The effect of a school-based iron intervention on the haemoglobin concentration of school children in north-west Pakistan

Objective: To assess the effectiveness of iron supplements administered to school children through a longitudinal school health intervention in terms of child haemoglobin concentration and anaemia prevalence. Subjects and Methods: Children and adolescents aged 5-17 years were selected from 30 schools in north-west Pakistan for a longitudinal iron supplement intervention. Children received once-weekly iron supplements (200mg ferrous sulphate containing 63mg of elemental iron) for 24 weeks (n=352); or the same supplements twice-weekly for 12 weeks (n=298) or received no tablets (n=298). Haemoglobin concentration was estimated in finger-prick blood samples at baseline, 12 and 24 weeks. Follow-up samples were taken at 36 weeks. Results: A non-significant increase in haemoglobin concentration was observed in children receiving iron supplements after 12 weeks (mean 1.4 g/l SD 15.0 g/l in once-weekly vs 2.5 g/l SD 14.5 g/l in twice-weekly) compared with the group receiving no iron supplements. There was no significant reduction in the prevalence of anaemia in the once-weekly or twice-weekly group compared with the unsupplemented group. The prevalence of anaemia increased in all three groups during the follow-up period (24 to 36 weeks). Conclusion: Once-weekly and twice-weekly iron supplements were not associated with significant increases in haemoglobin concentration compared with unsupplemented children. In all groups, baseline haemoglobin concentration was the strongest predictor of haemoglobin increase. The lack of improvement may stem from the moderate baseline prevalence of anaemia (33%); other micronutrient deficiencies; variable compliance, or the worsening of haemoglobin status due to seasonal changes in dietary iron and other nutrients.