Compression of Morbidity

The compression of morbidity refers to a theory about associations of health and disease with mortality in older life. Morbidity refers to diseases or symptoms of diseases and, more broadly, to problems with physical, cognitive, or emotional health, including limitations or disabilities that make it difficult to complete routine daily activities. Mortality refers to death. The compression of morbidity theory suggests that patterns of morbidity are changing in ways that can affect most people. The theory refers to postponing morbidity to late in life. If life expectancy remains constant, then postponing morbidity reduces the proportion of life during which the average person experiences morbidity. The theory suggests that, over time, populations in developed countries are experiencing such a compression of morbidity.

It is challenging to assess the validity of the compression of morbidity theory, however, because life expectancy has not remained constant. Life expectancy increased dramatically during the first half of the 20th century in countries throughout the world and has continued to increase in most groups in many developed and developing countries since then, although more slowly. When people live to older ages, their risks of developing diseases or becoming disabled increase greatly.

So a fundamental question in lifespan research is whether the large increase in life expectancy has increased or reduced the proportion of life with morbidity. This entry first explains the compression of morbidity. Next, it briefly describes two other theories of population health and applies all three theories to examine trends in population health, with a focus on studies conducted in developed countries throughout the world. Finally, it describes implications of the compression of morbidity.