Education, gender, and the compression of morbidity

According to the Compression of Morbidity (CM) hypothesis, people who exercise, eat nutritiously, do not smoke, and maintain good weight, i.e., people who practice healthy habits, will be more likely to live free of disabling diseases and injuries up until the last few months or years of life. The Increasing Misery (IM) hypothesis, on the other hand, holds that preventive health measures will extend life expectancy but will also increase the number of infirm years. The CM theory implies that curves of morbidity or disability with age should become increasingly "rectangular" for groups who practice healthy habits in the broadest sense. The IM theory does not. This Rectangularization hypothesis is examined with cross-sectional data measuring disability from the Epidemiological Follow-up to the National Health and Nutrition Examination Survey, I (NHEFS), using years of schooling as the independent variable proxy representing favored health status, and examining interactions with age. A modified version of the Disability Index (DI) from the Stanford Health Assessment Questionnaire (HAQ) is used to measure disability. In some analyses, deceased subjects were assigned the worst disability score. Four subsamples of women and men, fifty years old and over, alive and deceased in 1982-84, were analyzed. Female, and especially male, subsamples which included the deceased provided evidence for the CM hypothesis. Results for the subsamples of those remaining alive in 1982-84 were ambiguous. However, lifetime (over age 50) cumulative disability was 21 to 60 percent less for the more educated than the less educated, depending upon whether deceased were included or excluded. If higher education level is an appropriate surrogate for the effect of good health practices, then extending such practices will result in less, rather than more, lifetime disability.