Education, income, and functional limitation transitions among American adults: Contrasting onset and progression
Background: Although a robust association between socioeconomic status and health has been shown in past research, the processes that explain the connection are not well understood. This paper seeks to advance such understanding in two ways, first by attending to the distinction between onset of a functional health problem and its progression, and second by addressing whether and how education and income relate differently to the onset versus progression of functional health problems. Methods: Data come from the Americans' Changing Lives survey (n = 3617). The baseline was conducted in 1986 and outcome status measured in 1994. Activity limitations are categorized into none, mild, moderate, severe. Onset is defined as having no limitation at origin and a limitation at outcome. Progression is defined as limitation of a particular severity at origin and improving, staying the same, or getting worse with respect to the severity. Multinomial regressions determine transition probabilities related to onset and progression. Results: Those with higher income and education are less likely to experience an onset. Only income associates with progression. Those with the highest income are most likely to improve and least likely to get worse in comparison to those with the lowest income. Conclusions: Education, being determined early in life and influencing psychosocial mechanisms throughout life, may have a greater impact on prevention of activity and functional disorders. Income's role may be both as a prevention factor and as a mechanism for management of health problems.
Zimmer, Zachary and James S. House. 2003. "Education, income, and functional limitation transitions among American adults: Contrasting onset and progression," International Journal of Epidemiology 32(6): 1089–1097.