Context: The existence of a positive relationship between income and morbidity has been well documented in the literature. But it is unclear whether the relationship is positive because increased income allows individuals to purchase more health inputs that improve their health, because healthy individuals are more productive and thus can earn higher wages in the labor market, or because a third factor is improving health and increasing income. This article explores whether increases in income improve the health of the low-income population.
Methods: Because health status may affect income, this article uses an “instrumental variable” strategy that considers income variations over seventeen years of changes in the generosity of state and federal Earned Income Tax Credits (EITC, a measure that should be exogenous to health status). I measured health status using both the self-reported health status and the functional limitations indicated on the Survey of Income and Program Participation (SIPP), as well as the self-reported health status indicated on the March Current Population Survey (CPS).
Findings: I found only limited support for the theory that the relationship between income and morbidity is derived from shifts in income. Although I did observe a correlation between income and self-reported health, I found no evidence that increases in income significantly improve self-reported health statuses. In addition, while increases in income appear to reduce the prevalence of hearing limitations when using corrective measures, these increases did not have a significant effect on most of the other functional limitations considered here.
Conclusions: These findings suggest that the ability to improve short-term health outcomes through public transfer payments may be limited. However, the lifetime effects on the health of people with higher incomes would still be a valuable avenue for future research.