Income, Self-Rated Health, and Morbidity. A Systematic Review of Longitudinal Studies.

If people were asked whether income changes influence self-rated health and morbidity, they would probably answer yes. Indeed, previous studies validated this assumption, but most of them used cross-sectional data and only considered self-rated health as the decisive factor. On the other hand, there are a few studies using longitudinal data, which found a much smaller association between income and self-rated health. In order to give a conclusive overview of the current study situation, this review summarizes and examines studies which use only longitudinal data. In addition to self-rated health, the effects of income on the objective factor of morbidity were also investigated. The review includes a total of 14 papers that use data from seven different countries. It concludes that there is a small, statistically significant, positive impact of increased income on self-rated health, but a negative association between income growth and morbidity. Taking the limitations of confounders, attrition, and selection bias into account, the results may even be insignificant.