Modification of the Cardiovascular Effects of Temperature by Neighborhood Socio-Economic Deprivation

Abstract

Background: Ambient daily temperature, both elevated and low, has been associated with daily cardiovascular mortality; studies have consistently observed larger associations for neighborhoods of higher socio-economic deprivation (NSED). However, no study has assessed whether NSED modifies the timing of this effect. We investigated how NSED modifies the association between daily temperature and risk of myocardial infarction (MI) in New York City (NYC).Methods: We used 2000-2015 MI hospitalization and residence data from the Statewide Planning and Research Cooperative System (SPARCS) dataset of the New York Department of Health. Temperature and relative humidity came from the North American Land Data Assimilation System (NLDAS) at 11x14 km2 resolution. We aggregated data to 42 neighborhoods defined by NYC Department of Health. We estimated NSED with a Neighborhood Deprivation Index (NDI), from principal components analysis of US Census variables. We employed a time series design with a distributed lag nonlinear model for 14 days lag of temperature. We controlled for seasonality, long-term trends, relative humidity, NDI, and random effects for neighborhood. We then stratified by NDI quartile.Results: We observed 329,457 MI hospitalizations over the study period. Same-day high temperature was nonlinearly associated with MI; an increase from mean temperature (12.3oC) to the 95th percentile (28oC) was associated with a 7.0% increase (95%CI: 3.7, 10.4%) in MI hospitalization rate. The second quartile of NDI showed the largest association (8.6%; 95%CI: 5.2, 12.0%); the least deprived quartile had the smallest association (6.0%; 95%CI: 2.6, 9.4%). For all subpopulations, only same-day temperature was statistically significant.Conclusion: Our findings suggest that same-day temperature is associated with daily MI rates, across levels of NDI, and this was strongest in the second-most-deprived neighborhoods. The timing of the association was consistent across quartiles of NDI. Further research is needed to elucidate factors that provide resilience to heat exposure.