The prevalence of anaemia could fall by almost 21 percentage points in children and over 28 percentage points in non-pregnant women depending on the method and site of blood collection. This was stated in a study published recently in the journal BMJ Global. These findings call the global estimates of anaemia prevalence, which have been predominantly generated using capillary (or fingertip) measurements, into doubt, stated the study.
This was earlier also flagged by Indian experts who had analysed data from the Comprehensive National Nutrition Survey (CNNS) in 2019. In a paper based on the CNNS survey published in June 2021 in the medical journal, The Lancet, the authors had stated that “datasets, including those from India in field settings, indicate a higher haemoglobin estimate (up to 0·6–0·9 g/dL) in venous blood than in capillary samples.”
The BMJ Global study done by a group of infectious diseases experts, maternal and child health specialists and haematologists from Australia, Bangladesh, Malawi and the US looked at the difference in measurement of haemoglobin concentration in blood drawn from the veins (venous) as opposed to that drawn from the capillaries in children and pregnant women.
Accurate and precise measurement of haemoglobin concentration is critical for estimation of population level anaemia prevalence, which forms the basis for defining nutrition policy choices and monitoring programmes, noted the study. It added that population-based anaemia prevalence statistics derived from capillary haemoglobin concentrations may be inaccurate and lead to incorrect classifications of public health severity.