Meta-analysis of multilevel studies finds narrowing rich-poor divide improves health of all
WEDNESDAY, Nov. 11 (HealthDay News) -- Income inequality has an adverse outcome on health, and narrowing the divide between the rich and poor yields health benefits across society, not just to the poor, according to a study published online Nov. 10 in BMJ.
Naoki Kondo, M.D., of the University of Yamanashi in Japan, and colleagues conducted a meta-analysis of nine cohort studies comprising 59,509,857 subjects and 19 cross-sectional studies comprising 1,280,211 subjects to calculate the overall risk of mortality and self-related health.
With each 0.05 unit increase in Gini coefficient, a measure of societal income inequality, there was an increased risk of mortality and poor self-related health, the researchers found. There appeared to be a threshold of income inequality beyond which the adverse health impact began to emerge, the investigators discovered, as the association was stronger among studies with a Gini coefficient of 0.3 and above.
"The results suggest a modest adverse effect of income inequality on health, although the population impact might be larger if the association is truly causal," the authors write. "The findings need to be interpreted with caution given the heterogeneity between studies, as well as the attenuation of the risk estimates in analyses that attempted to control for the unmeasured characteristics of areas with high levels of income inequality."
The study was supported by the Pfizer Health Research Foundation.