Study suggests anaemia is being over-diagnosed in India

It emphasises need to re-examine WHO haemoglobin cut-offs to define anaemia and see the ailment in more region-specific ways

Updated - June 18, 2021 03:30 pm IST

Published - June 18, 2021 03:05 pm IST - Bengaluru

The cut-off currently set by the WHO is 12 gm/decilitre for women, and between 11 and 12 gm/decilitre at different ages for boys and girls.

The cut-off currently set by the WHO is 12 gm/decilitre for women, and between 11 and 12 gm/decilitre at different ages for boys and girls.

The National Family Health Survey – 5 data has shown that India’s anaemia situation has remained unchanged from the high prevalence of nearly 60% reported in the NFHS-4 survey in 2015.

The NFHS-5 indicated that there was a high anaemic population of Indian women and children that had not responded to the various iron supplementation and food fortification programs implemented in the last five years.

However, a team of researchers from the Sitaram Bhartia Institute of Science and Research, New Delhi, St. John’s Medical College, Bengaluru, and the Indian Institute of Population Sciences, New Delhi, said it is possible that anaemia is being over-diagnosed in India due to a wrong (higher than appropriate) haemoglobin diagnostic cut-off.

In their recent paper published in the Lancet Global Health, these researchers asserted the need for re-examination of WHO haemoglobin cut-offs to define anaemia.

The corresponding authors of the paper Prof. Harshpal Singh Sachdev and Prof. Anura V. Kurpad told The Hindu that if the haemoglobin diagnostic cut-off is inappropriately high, then a falsely high proportion of anaemia will be detected in the population.

WHO standard

The cut-off currently set by the WHO is 12 gm/decilitre for women, and between 11 and 12 gm/decilitre at different ages for boys and girls.

The researchers used data from the Comprehensive National Nutrition Survey (CNNS) carried out in 2016-18 (under the aegis of the Ministry of Health and Family Welfare in collaboration with UNICEF and the Population Council) with a statistical approach.

“The CNNS is an exhaustive and quality-controlled survey, measuring a number of biomarkers of health and nutrition with great precision in venous blood sampled from a very large number of children across India. The prevalence of anaemia in these children was 35%, when using the WHO cut-off, lower than what the NFHS surveys have found,” said the researchers.

Prof. Kurpad said the extreme low value in a representative healthy population of children (surveyed in the CNNS), or the 2.5th centile of the distribution of Hb values, was chosen as the Hb cut-off to diagnose anaemia. “This method is the standard way in which the current cut-off was defined by the WHO with one caveat: in that definition, a population of predominantly white people was used. It is now thought that normal haemoglobin levels vary across different parts of the world, and diagnostic cut-offs need to be defined in more region-specific ways,” he asserted.

“The Indian cut-offs based on the CNNS were lower than the current WHO cut-off, across all ages from 1-19 years in boys and girls. If the proposed new anaemia cut-offs were used, it would reduce the anaemia prevalence in Indian children to one-third of the present value. That is, the burden of anaemia would fall from 35% using the current WHO cut-off, to nearly 11%,” he explained.

The authors also pointed out that this might also be a reason why the response to various interventions is small and stagnant. “If the prevalence is truly low, then the corrective response will also be low,” they added.

Sampling method

The study also pointed to differences in the way blood is drawn for sampling in CNNS and NFHS. Prof. Sachdev said that NFHS survey measured haemoglobin in a drop of capillary blood that oozes from a finger prick. “This can dilute the blood and give a falsely lower value, and consequently it will appear that there was a higher prevalence of anaemia in the population. The CNNS survey used the recommended method of venous blood sampling and gave accurate values,” he said.

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