Life expectancy at birth measures the average number of years that a newborn baby can expect to live. This estimation is usually based only on the mortality rates of the population in a given year. Life expectancy at birth increased dramatically during the 20th century due to improved sanitation and public health. However, higher life expectancy is desirable only if it is linked to acceptable level of quality of life (healthy years of life).
In 1999, the World Health Organization (WHO) developed a new measure of population health: the disability-adjusted life expectancy (DALE) measures the equivalent number of years of life expected to be lived in full health, also called ‘healthy life expectancy’. DALE is defined as the total life expectancy based on average numbers of years males and females could expect to live in each country, minus the expected years of good health lost due to disability.
DALE at birth is higher for women than men in most countries. However, although women live longer, they spend greater amount of life with disability. There are great variations in life expectancy worldwide. Genetically speaking, a baby born in Indian village is no different than a baby born in Tokyo. But the Indian baby has to face more communicable diseases, unsatisfactory dietary supplies, and lack of medical care. An adequate nutrition to mitigate the burden of chronic disease and disability has been identified as a key factor to increase the chance for a healthy life.
World ranking and healthy life expectancy (DALE) for selected countries