Association Between Air Temperature and Heart Disease Death Rates in Georgia Counties

Background: In this ecological study, global warming theory was tested on a local level, in Georgia. The hypothesis was that warmer counties would be associated with higher death rates. Methods: Heart disease death rates (HDDR) for 2008-2010 by Georgia county were compared to air temperature, also by county for the same years. Three race categories for HDDR were studied: black, white, and all races. Since there is evidence that living at higher land elevations provides a protective effect against heart disease, land elevation by county was included as a second predictor. Results: Correlation analyses revealed low strength, statistically significant correlations with white and all races HDDR as follows: direct for air temperature and indirect for land elevation. Correlations for blacks were negligible strength and statistically non-significant. Thus, multiple linear regressions (MLRs) were considered appropriate for whites and all race HDDR. In MLRs, temperature and elevation essentially cancelled each other relative to HDDR, resulting in statistically nonsignificant regression coefficients for each in both race categories (p \u3e 0.15). This may have in part been due to the slight collinearity that was observed between the two predictors (variance inflation factor = 10.6 for both predictors in both race categories). The study is limited by: a) its (ecological) design, where individual exposures are unknown; and b) the-less-than-ideal regression model that revealed slight collinearity between the predictors. Further research is required to verify these findings. Conclusions: In conclusion, this study did not reveal an adverse association between warmer counties and HDDR according to MLR