Using social security number to identify sub-populations vulnerable to the health impacts from extreme heat in Florida, U.S.

Abstract Background Some socioeconomically vulnerable groups may experience disproportionately higher risk of extreme heat illness than other groups, but no study has utilized the presence/absence of a social security number (SSN) as a proxy for vulnerable sub-populations. Methods This study focused on the warm season from 2008 to 2012 in Florida, U.S. With a total number of 8,256,171 individual level health outcomes, we devised separate case-crossover models for five heat-sensitive health outcomes (cardiovascular disease, dehydration, heat-related illness, renal disease, and respiratory disease), type of health care visit (emergency department (ED) and hospitalization), and patients reporting/not reporting an SSN. Each stratified model also considered potential effect modification by sex, age, or race/ethnicity. Results Mean temperature raised the odds of five heat-sensitive health outcomes with the highest odds ratios (ORs) for heat-related illness. Sex significantly modified heat exposure effects for dehydration ED visits (Males: 1.145, 95 % CI: 1.137–1.153; Females: 1.110, 95 % CI: 1.103–1.117) and hospitalization (Males: 1.116, 95 % CI: 1.110–1.121; Females: 1.100, 95 % CI: 1.095–1.105). Patients not reporting an SSN between 25 and 44 years (1.264, 95 % CI: 1.192–1.340) exhibited significantly higher dehydration ED ORs than those reporting an SSN (1.146, 95 % CI: 1.136–1.157). We also observed significantly higher ORs for cardiovascular disease hospitalization from the no SSN group (SSN: 1.089, 95 % CI: 1.088–1.090; no SSN: 1.100, 95 % CI: 1.091–1.110). Conclusions This paper partially supports the idea that individuals without an SSN could experience higher risks of dehydration (for those 25–45 years), renal disease, and cardiovascular disease than those with an SSN.