Differences in County-Level Cardiovascular Disease Mortality Rates due to Damage Caused by Hurricane Matthew and the Moderating Effects of Social Capital: A Natural Experiment

Abstract

Abstract BackgroundAs the climate continues to warm hurricanes will continue to increase in both severity and frequency. Hurricane damage is associated with cardiovascular events, but social capital may moderate this relationship. We examined the association between county-level hurricane damage and cardiovascular mortality rates after Hurricane Matthew, and the moderating effect of several aspects of social capital on this relationship in post-disaster contexts. Social capital refers to the social relationships and structures that provide individuals with material, financial, and emotional resources throughout their lives. Previous research has found an association between high levels of social capital and lower rates of cardiovascular disease (CVD) mortality. In post-disaster settings, social capital may protect against CVD mortality by improving access to life saving resources. We hypothesized that higher (vs. lower) hurricane damage would be associated with higher CVD mortality and measures of social capital would be associated with decreased CVD mortality in counties affected by Hurricane Matthew.MethodsCounty-level social data (n = 183) were compiled from federal surveys before and after Hurricane Matthew to construct, per prior literature, a social capital index based on four dimensions (sub-indices): family unity, informal civil society, institutional confidence, and collective efficacy. CVD mortality rate was constructed from epidemiological data. Changes in CVD mortality based on level of hurricane damage were assessed using regression adjustment. We used cluster robust Poisson population average models to determine the moderating effect of social capital on CVD mortality rates in both high and low damage counties.ResultsWe found that low levels of hurricane damage are associated with increased CVD mortality rates. Among the different social capital dimensions, institutional confidence was associated with reduced initial CVD mortality in high- damage counties (p ≤ .001), but its association with CVD mortality trends was null. The overall effects of social capital and its sub-indices were largely nonsignificant. ConclusionLow levels of hurricane damage are associated with increased CVD mortality for 18 months after Hurricane Matthew. The role of social capital remains unclear. Future research should focus on improving measurement of social capital and quality of hurricane damage and CVD mortality data.