The use of biomarkers in the Longitudinal Ageing Study in India (LASI) has provided important insight into the health of India’s elderly population. LASI is the country’s first ageing study, with a sample size of 72,250 individuals aged 45 and above. The study includes three schedules, namely the individual, the family, and the community which have an impact on the health, economic, and social determinants, and their effects on population ageing in India. The incorporation of biomarkers was an important innovation in India’s LASI, especially because of the low levels of education and a lack of awareness and access to healthcare services. LASI incorporates the biomarker module in the individual survey for all respondents 45 years or older. Biomarkers show the prevalence of chronic health conditions such as hypertension, visual impairment, obesity, undernutrition, and chronic respiratory diseases based on direct health examinations.

In LASI, the biomarker test was performed using standard devices and calibration of the devices was ensured regularly to ensure accuracy of the results. Physiological assessment, anthropometric measurement, performance-based measurement, and a dried blood spot test are part of biomarker tests performed under LASI.

A biomarker is a characteristic that can be measured and evaluated independently as an indicator of normal biological processes, pathogenic processes, or pharmacological response to a therapeutic intervention. [1]

Physiological assessment

  • Blood pressure and pulse measurement: These were measured using the Omron B.P. monitor. Blood pressure and pulse were measured three times with an interval of one minute between each reading.  
  • Lung function test:  This is a gold standard test for the diagnosis of obstructive airways diseases (OAD), including asthma and chronic obstructive pulmonary disease (COPD). In LASI, the lung function test was performed using a spirometry device called as ‘Thor’ spirometer. 

Anthropometric measurement

  • Height and weight measurement: Height was measured using a pocket stadiometer and weight was measured using a digital weight measuring scale. Body Mass Index (BMI) was calculated from height and weight, to indicate the nutritional status such as underweight, normal, overweight, and obese. 
  • Waist and hip circumference:  This was measured using Gulick‘s soft tape. The Waist to hip ratio was calculated using the waist and hip measurements. This ratio predicts cardiovascular risks and metabolic changes that increase the risk of hypertension and diabetes.

Performance based measurement

  • Grip strength: This is an important biomarker of health and ageing because it measures muscle mass and upper body strength. Smedley’s Hand Dynamometer was used to measure grip strength.
  • Balance test: The mid-level balance test (semi-tandem) was performed first, followed by testing the full tandem or side by side stance based on the results of the semi-tandem test. Balance tests were found to be helpful predictors of outcomes such as mortality, disability and the risk of falls.
  • Timed walk: Walking speed predicts overall health, disability level, future need for health care, and mortality in the elderly. In this test, respondents had to walk twice for a distance of 4 metres on a walking course and their walking speed was noted using a stop watch.  
  • Vision test: The CAPI-based tumbling E LogMAR chart was used to measure both near and distance vision of both eyes. The distance vision was measured at 3 m, while the near vision was measured at a 40 cm distance.

Dried blood spot test

  • Dried blood spot specimens were collected on specially designed absorbent filter paper by adding a few drops of blood, taken from the finger drawn by the lancet. This dried blood spot was used for detection of anaemia and other disease conditions. 

The data of LASI wave 1 was released on 6th January 2021 by Dr. Harsh Vardhan, Hon’ble Union Minister of Health and Welfare, Government of India. 

The few findings of biomarker are listed below

  • High blood pressure was found among 37 percent of the elderly aged 60 and above whereas its incidence was less common  among older adults aged 45-59 years at 25 percent. Furthermore, the prevalence of high blood pressure was higher in urban areas as compared to rural areas. more 40 percent of the elderly aged 60 and above in urban areas had blood pressure as against 35 percent in rural areas. Moreover, the prevalence was higher among women at 38 percent than among men at 34 percent.
  • Nearly half (49 percent) of older adults 45 and above in India suffer from either restrictive or obstructive pulmonary diseases, highlighting the poor respiratory health condition of older adults.
  • In India, 31 percent of older adults aged 45 and above have either low near or low distance vision. Over one-third of older adults aged 60 and above (37 percent) have low vision in India compared to 26 percent of 45-59-year-old adults.
  • More than a quarter (27%) of adulta 60 years and older are underweight and a fifth (22%) of them are overweight. This shows the dual burden of undernutrition and overnutrition among the elderly. Obesity was higher among older adults aged 45-59 (9 percent) than among the elderly 60 years and above (6%).  The prevalence of underweight among elderly aged 60 and above in rural areas is nearly three times (32%) as compared to urban areas (12%) 

Biomarker measurements are an important tool to identify diseases in their early stages and monitor disease patterns. They can serve as an effective surveillance tool, as well as help evaluate intervention programs. In the broad areas of social, health and economic well-being, the evidence coming out of LASI would be helpful in designing policies and programs for older people.

About LASI

The Longitudinal Aging Study in India (LASI) is a nationally-representative, longitudinal survey to examine aging and retirement among India’s 45+ population.  It is a joint undertaking of the Harvard T.H. Chan School of Public Health, the International Institute for Population Sciences (IIPS) in Mumbai, India, and the University of Southern California (USC).  

-Sushma Marita

[1] https://www.news-medical.net/health/What-is-a-Biomarker.aspx

Photo Credits: Agewell

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