Trends and Differentials in Disability-Free Life Expectancy: Concepts, Methods, and Findings
Citation: Robine, Mathers, Brouard (1996) Trends and Differentials in Disability-Free Life Expectancy: Concepts, Methods, and Findings.
Notes: The WHO has proposed the following model of irreversible disorders: disease-impairment-disability-handicap. Impairments are abnormalities of body structure and appearance with organ and system function, resulting from any cause at the organ level. Disabilities reflect the consequences of impairment in terms of functional performance and activity by the individual person-level. Handicaps are concerned with the disadvantages experienced by the individual as a result of impairments and disabilities related to individual's surroundings. Theories of health transition and disability Pandemic of disabilities: the postponement of death results in a worsening of the severity of chronic diseases because mortality decline is due to a decline in the fatality of chronic diseases and not a decline in their incidence or progression decline in the ratio of disability-free life expectancy to total life expectancy (DFLE/LE) Compression of morbidity: if morbidity is defined from the onset of chronic infirmity until death and if the onset can be postponed and if adult life expectancy is relatively constant, then morbidity will be compressed into a shorter period of time increase in DFLE/LE ratio. Dynamic equilibrium: the increase in life expectancy is in part explained by a slowing down in the rate of progression of chronic diseases; therefore, although the decline in mortality leads to an increase in the prevalence of chronic diseases, these diseases will in general be milder in character decline in DFLE/LE ratio, increase or leveling off in ratio of severe DFLE/LE. Using data from France from 1900 to 1990, Robine and Mathers (1993) simulated various possible trends in DFLE. They found that absolute compression of morbidity is only obtained when the prevalence of disability falls at a faster rate than mortality. (This is a sort of random thing in this summary, but it felt the same way in the article.) In a meta-analysis of comparisons of existing international data series, the authors compare 5 areas: 1. Gender differentials: Although most studies indicate that life expectancy and DFLE are greater for females, they also show that their proportion of disability-free years to total life expectancy is slightly lower than males. 2. Socioeconomic differentials: Well-known socioeconomic differences in life expectancy increase markedly when the calculations are done for DFLE 3. Causes of disability and mortality: The elimination of some causes have a greater effect than others. 4. Time trends: Overall, studies suggest that, over the last 25 years, there has been a 6-year increase in life expectancy at birth among females in developed countries. By contrast, there has been a corresponding stagnation at 63 years in DFLE. These results tend to confirm the theory of dynamic equilibrium proposed by Manton (1982). Geographical comparisons: are difficult to make. Combining the data from different countries does not allow one to reliably determine whether or not the proportion of DFLE decreases as overall life expectancy increases.