Regional Demographic and Epidemiologic Transitions

Demographic and epidemiologic transitions

The demographic transition results in lower proportions of children, an adult population growing faster than the entire population, and an emerging elderly population. Developed countries made this transition decades ago. The epidemiologic transition, first described by Omran in 1971, begins with a phase of pestilence and famine and a low life expectancy of 20–30 years, then shifts to a phase of receding pandemics and an increase in life expectancy of 40–50 years, then progresses to a phase where life expectancy is 60 years and above, and chronic diseases become the leading cause of death. South Asia is shifting from the second to the third phase.

A fourth phase of the epidemiologic transition

It has been described as the age of “delayed chronic diseases” reflecting new science and understanding that chronic diseases with aging are not inevitable. In developed countries where people are living longer than they used to, there is a compression of morbidity, that is, longer-living people do not spend more years in poor health. The reasons for this trend seem to include better nutrition, sanitation, and hygiene, as well as the spread of medical knowledge and its application.

In most developing countries, population aging is happening much faster than it did in developed countries earlier. The result is that, compared to developed countries, increased longevity has not been accompanied by increased personal income; there are also less extensive social welfare and public health provision, leaving the aging process unaccompanied by compression of morbidity.

In addition, NCDs moving into younger adult population groups in developing countries can result in premature disability and withdrawal from the labor market. Both unhealthy aging and premature disability, in turn, may result in less favorable dependency ratios and dampen the potential
demographic dividend