Trends in Functional Limitations: Are Older Americans Living Longer and Better?

One aspect of health is the ability to carry out simple physical tasks, and a recent study by RAND researchers Vicki Freedman and Linda Martin finds that the percentage of older Americans with limitations in functioning decreased from 1984 to 1993. This new evidence gives credence to the view that the health of older Americans, as well as their survival, has been improving. In their paper, "Understanding Trends in Functional Limitations Among Older Americans," which was recently published in the American Journal of Public Health, Freedman and Martin explore the factors underlying these trends and attempt to determine whether the trends truly represent changes in the underlying health status of older Americans, or whether they are a result of other influences.

Measuring Functioning

Freedman and Martin note that these measures are potentially influenced by living environments and socially defined roles. For example, the ability to bathe may be facilitated by using a walk-in shower or impeded by having to climb over the edge of a bathtub, and whether an older person is able to do the laundry may depend on that person's expectations about the appropriateness of the task. Thus, aggregate reported changes in the population in the ability to carry out these two specific activities may not represent true changes in underlying health but rather changes in the proportion of older Americans who have the resources to remodel their bathrooms or who think it is appropriate to do their own laundry.

Instead, Freedman and Martin employ four measures--known as measures of functional limitations--that more closely approximate true physiological capabilities and that can be tracked over time for the older American population:

• Difficulty seeing the words and letters in a newspaper

• Difficulty lifting and carrying a 10-pound weight

• Difficulty climbing a flight of stairs

• Difficulty walking three blocks or a quarter of a mile.

Functioning Has Improved

Using data from the nationally representative, household-based Survey of Income and Program Participation (SIPP), the researchers analyze changes in the rates of functional limitations for five age groups: 50 to 64 years, 65 to 79 years, 80 and older, 50 and older, and 65 and older. Unlike other studies, they include the 50-to-64 age group because of interest in changes in health at the ages when retirement decisions are often made.

For the period 1984 to 1993, the researchers find large declines in the prevalence of functional limitations across all five age groups. The extent of the improvement varies with age, with the smallest absolute gains occurring among those ages 50 to 64 and the largest occurring among those ages 80 and older. In the aggregate, the population ages 50 and over experienced the following changes:

• 3.7 percentage point decline in difficulty seeing (from 15.3 percent to 11.6 percent )

• 4.6 percentage point decline in difficulty lifting and carrying (from 23.5 percent to 18.9 percent)

• 2.5 percentage point decline in difficulty climbing (from 24.5 percent to 22.0 percent)

• 3.5 percentage point decline in difficulty walking (from 25.8 percent to 22.3 percent).

SOURCE: Vicki A. Freedman and Linda G. Martin, American Journal of Public Health, Vol. 88, No. 10, 1998.

^aAdjusted for age, sex, marital status, race, ethnicity, education, ownership of liquid financial assets, and region of residence.

^bIn percentage.

*Not statistically significant at the .05 level.

Thus, Freedman and Martin are able to home in on a "purer" measure of health and minimize the possible influence of changes in living environments and role expectations over the nine-year period. They factor out the influence of changes in population composition and, for the function of walking, changes in assistive device use. Although they are not able to consider all possible explanations in their models of functioning (e.g., they have no measures of trends in the prevalence of specific diseases and conditions), they factor out many of the possible causes. Accordingly, they conclude that the improvements in functioning strongly suggest improvements in underlying physiological capabilities.

Implications for the Future

The results of this study indicate that the older population today is functioning significantly better than that of just a decade ago. The researchers caution, however, that these downward trends in the prevalence of functional limitations will not necessarily continue. Much work remains to determine the specific physiological causes of the improvements, so it is difficult to predict whether and to what extent the trends will continue. Even if they were to continue, the absolute number of disabled individuals is likely to increase, given the expected growth in the older population. Thus, planning for the needs of a growing number of disabled people will remain a challenge. However, if these downward trends do continue, relatively fewer older Americans will need the medical care and support services associated with limitations, and a greater proportion of the older population should be able to work and live independently.