Income differentials in functional disability in old age: relative risks of onset, recovery, decline, attrition and...

Socioeconomic status (SES) differences in health decline in late life may be underestimated, because the relatively higher risks of attrition of lower-SES persons are seldom taken into account. This longitudinal study aimed at comparing income differences in the course of disability, non-mortality attrition and mortality in older adults.

A sample population of 3107 older adults who participated in the 1992/1993 baseline of the Longitudinal Aging Study Amsterdam was examined regarding changes in functional disability in 1998/1999. SES was indicated by household income.

Multinomial regression analyses revealed that, for men without disability at baseline, the relative rate for attrition was four times higher and the mortality rate was twice as high for low-income vs high-income persons. For non-disabled women, the relative risk for the onset of disability was nearly twice as high for low-income vs high-income persons. For both men and women, these risks decreased only slightly when behavioral and psychosocial risk factors were taken into account. Among persons with disability at baseline, the relative risks for attrition (for women) and mortality (for men) were twice as high for low-income persons, but no income differences were found with respect to recovery and decline. Adjustment for risk factors decreased the relative risks for attrition and mortality to a non-significant level.

Income inequality in health in late life is to a large degree explained by the higher incidence of disability among lower-status women and by the higher attrition and mortality risks among lower-status men.