Contribution of Chronic Conditions to Aggregate Changes in Old-Age Functioning.

Contribution of Chronic Conditions to Aggregate Changes in Old-Age Functioning Freedman VA, Martin LG (Polisher Research Institute, Philadelphia Geriatric Center, Jenkintown, Pa; Population Council, New York, NY), Am J Public Health. 2000;90:1755-1760.

Does the postponement of death: (a) increase chronic disease and disability; (b) compress the morbid period; or (c) create dynamic equilibrium, where chronic diseases increase but their progression is slowed? This article explored these competing theories by examining data from the Supplements on Aging to the 1984 and 1994 National Health Interview Survey (NHIS), the primary source of health information on the civilian noninstitutionalized population of the United States. The supplement to the 1994 survey was not completed until 1995.

The authors focused on functional limitations rather than difficulty with activities of daily living because task components are less sensitive than the task itself to changes in a person's expectations. The data collected involved 7,527 people over 70 years of age who lived in the community in 1984 and 9,245 in 1995. The authors adjusted the weights for the 1995 supplement to allow for an accurate comparison. They acknowledged that omission of people living in institutions could bias estimates of change.

The two Supplements on Aging asked identical questions regarding functional limitations, allowing the authors to develop two scales reflecting upper- and lower-body tasks. The supplements also asked questions about chronic disease, including hip fracture, stroke, osteoporosis, arthritis, and obesity; no questions, however, were asked regarding dementia. The authors reported that wording changes regarding arthritis and heart disease between the 1984 and 1995 supplements increased the estimates for these conditions.

Statistical analyses of changes in the prevalence of limitations, chronic conditions, and demographic factors were performed using chi-square distribution tests. Least square regression models were used for effects of disease on function. Changes in the effects of conditions over time were tested with non-stratified models, with the year interacting with the variables. All statistical tests and confidence intervals were based on adjusted standard errors to account for the survey design.

The results indicated that the percentage of people over 70 years of age with upper-extremity and lower-extremity limitations declined from 1984 to 1995. The percentage of people with upper-extremity limitations declined from 5.1% to 4.3%, and the percentage of people with lower-extremity limitations declined from 34.2% to 28.5%. Reports of disabling chronic diseases, however, increased; only reports of hypertension decreased. Both surveys showed an increase in limitations as being a direct link to the presence of a chronic condition, particularly hip fracture and stroke.

The 1995 survey revealed that several chronic diseases had less effect on function than in 1984. For the upper extremity, osteoporosis, heart disease, and arthritis showed significantly less debility, whereas, for the lower extremity, osteoporosis and arthritis showed decreased debility. Overall, the increase in reports of chronic conditions in 1995 was completely offset by the decreased reports of associated limitation for the upper extremities and was partially offset by the decreased reports of associated limitation for the lower extremities.

Based on their analysis, the authors concluded that certain major diseases, notably arthritis, have become less debilitating and that function in old age is improving. The authors speculated that the increased prevalence of certain conditions may be the result of better detection and education and that the decreased disability may be the result of improved treatments.

The authors concluded that improved functioning is not a result of primary prevention and that their results indicated an increase in disease rather than a decrease. They also believed that their evidence seems to support the dynamic equilibrium theory, but the evidence cannot confirm this conclusion.

Chris Childers, PT
Salt Lake City, Utah