Anaemia and iron deficiency in India: a venous blood-based survey of adolescents, adults, and the elderly in eight states.

Background: Surveys based on capillary blood show that anaemia is rampant in India, but capillary blood haemoglobin (Hb) may not accurately reflect venous blood Hb concentrations. Further, iron deficiency (ID) is thought to be the main cause of anaemia, there are no venous blood-based surveys to confirm this.

Methods: A community-based (urban, slum and rural) cross-sectional, venous blood survey was conducted in eight Indian states to estimate anaemia and ID prevalences from Hb and inflammation-corrected plasma ferritin concentrations in adolescents, adults, and elderly.

Results: The prevalence of anaemia was 44%, 41% and 45% in adolescent girls, adult and elderly women respectively, compared to 24%, 21% and 37% in adolescent boys, adult, and elderly men. The overall prevalence varied widely, ranging from 12% in Meghalaya to 70% in Assam. Mild anaemia prevalence was predominant at about half of overall anaemia prevalence. ID-associated anaemia (IDA) prevalence was less than a third of the overall anaemia prevalence, and varied among age and sex groups, approaching 45% only in adolescent girls. IDA prevalence was even lower in the mild anaemia group. Thus, the major proportion of anaemia in all groups was associated with 'other' causes.

Conclusions: Anaemia prevalence, when measured by venous blood Hb, was substantially lower than earlier capillary blood-based estimates and was predominantly of the mild variety. The prevalence of IDA was also much lower than anticipated; therefore, the aetiological role of ID appears not to be predominant. These results have policy implications for anaemia prevention and correction at the population level.