The complete article is on-line (free!). It might seem obvious that poorer older people have lesser physical function than those better off, but the article discusses early work history, smoking, education, and earlier age at death also.
Gradient of Disability across the Socioeconomic Spectrum in the United States
Meredith Minkler, Dr.P.H., Esme Fuller-Thomson, Ph.D., M.S.W., and Jack M. Guralnik, M.D., Ph.D. New England Journal of Medicine, Volume 355:695-703, August 17, 2006 , Number 7
Background: Although the relationship between extreme poverty and poor health among older adults has long been recognized, less attention has been devoted to investigating whether a gradient in disability exists in the United States among persons with middle-class and upper-class incomes. We attempted to determine whether a gradient in functional limitation exists across the full spectrum of income among persons 55 years of age or older.
Methods: We obtained data from the Census 2000 Supplementary Survey, which used the methods and questionnaire of the American Community Survey, a nationally representative survey of 890,698 households with a response rate of 95 percent. Our sample included 149,000 men and 186,675 women who were at least 55 years of age, of whom 32,680 men and 48,111 women reported having a functional limitation (a long-lasting condition that substantially limited one or more basic physical activities, such as climbing stairs or lifting).
Results: A social-class gradient was observed for both men and women between the ages of 55 and 84, a gradient that held true even at the upper rungs of the socioeconomic ladder. For example, in comparison to persons between the ages of 55 and 64 who lived at 700 percent of the poverty line or above, persons of the same age but below the poverty line had six times the odds of reporting a functional limitation. With increasing income, the odds ratio declined. A significant gradient was present up to, but not beyond, the age of 85 years.
Conclusions: Our findings suggest that functional limitation in Americans between the ages of 55 and 84 years is inversely related to social class across the full spectrum of the socioeconomic gradient.