NFHS-6 not to measure anaemia as experts point out method is faulty

New Delhi: Questions related to anaemia have been dropped from the National Family Health Survey (NFHS-6) scheduled to start on July 6 after several experts pointed out that the method used to estimate anaemia in the survey was faulty, leading to overestimation. Moreover, anaemia is expected to be surveyed as part of the Diet and Biomarkers Survey in India (DABS-I), the preparations for which were launched in December last year.

In NFHS-5 for 2019-21, the prevalence of anaemia showed a huge ‘inexplicable’ jump among almost all sections with the most dramatic increase (from 59 to 67 per cent) among children aged 6 months to five years.

According to experts who were part of several meetings of the health ministry and Niti Aayog in which the decision to drop anaemia from NFHS was taken, the problem with the NFHS estimation was that it used capillary samples or blood drawn from a finger prick and then measured using an instrument whose results could vary by almost a gram per decilitre of blood.

In a study published in Lancet, which was based on data from India’s Comprehensive National Nutrition Survey (CNNS) in 2019, the authors showed that “data, 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.” Venous samples are blood samples drawn from veins and using these is said to be the gold standard to estimate anaemia.

“The DABS-I survey will map the diet, nutrition and health status, and provide a correct estimate of anaemia among urban and rural populations using venous samples and autoanalysers which have been standardised in the ICMR-NIN labs. It is the first time that such a detailed study using biomarkers is being undertaken. The study will also provide nutrient composition data on cooked and uncooked foods from all regions and states of the country. While NFHS uses district-representative sampling, DABS will be using state and country-representative sampling. Pilots for DABS-I are ongoing in 12 states and the fieldwork for the survey is expected to start in a few weeks’ time,” explained Dr Hemalatha R, director of the National Institute of Nutrition, Hyderabad, which will be conducting the survey along with ICMR.

NFHS is conducted in almost 7 lakh sample households while DABS will be conducted on a sample of 1.8 lakh people across India. DABS is expected to be completed within a year.