Analysis of social determinants of health and extreme climate events: Identifying vulnerable populations and health outcomes in Jacksonville.

Background: Heatwaves and hurricanes pose risks to public health, especially for vulnerable populations. Methods: We assessed the impact of extreme weather events on health outcomes in socially vulnerable groups. We analyzed hospital mortality, acute stroke, myocardial infarction, and nonelective intensive care unit (ICU) admissions for 24,814 patients admitted to two hospitals in Jacksonville (2015-2017). We fitted modified Poisson regression models to assess differences relative to the heatwave and Hurricane Irma, presenting impacts with relative risks (RR) and 95% confidence intervals (CI). Results: There was no significant change in the rate of acute stroke or myocardial infarction during both the heatwave and Hurricane Irma. The rate of nonelective ICU admission showed no significant change during the heatwave and immediate posthurricane period (0-14 days after the hurricane) but increased during the extended posthurricane period (15-74 days after the hurricane) with an RR of 6.19 (95% CI = 1.25, 30.54) compared with the control period. Extreme climate events amplified disparities among vulnerable patient populations. During heatwave and extended posthurricane periods, the rate of acute stroke or myocardial infarction increased for elderly patients relative to younger patients with RRs of 1.43 (95% CI = 1.05, 1.94) and 1.53 (95% CI = 1.14, 2.07), and uninsured or Medicaid-insured patients relative to those with Medicare or private insurance with RRs of 1.71 (95% CI = 1.26, 2.33) and 1.88 (95% CI = 1.38, 2.59). Social vulnerability and air quality further impacted health outcomes during the extended posthurricane period, with a 0.1-unit increase in the Social Vulnerability Index score associated with a 65% decrease in risk of acute stroke or myocardial infarction with RR of 0.35 (95% CI = 0.16, 0.75) and a 69% decrease in risk of nonelective ICU admissions with RR of 0.31 (95% CI = 0.15-0.65), and a 1-unit increase in Air Quality Index value indicated a 2% increase in risk of acute stroke or myocardial infarction with RR of 1.02 (95% CI = 1.01, 1.03). Conclusions: Our findings suggest extreme climate events exacerbate negative health outcomes in socioeconomically vulnerable populations, underscoring the need for targeted public health interventions, improved healthcare access, and greater climate resilience in vulnerable communities.