Association of Temperature at Residence Vs Central Site Temperature with Mortality in Eastern Massachusetts-A Case Crossover Analysis

ISEE-0683 Background and Objective: Studies reported increased mortality during heat waves worldwide. While these studies used daily central site temperature as the exposure variable, temperature is spatially variable, and housing and landscape characteristics affect exposure. To investigate acute and chronic effects of temperature on mortality we developed a spatio-temporal model for temperature in Eastern Massachusetts for 2000 to 2004 and applied it to a case-crossover study. Methods: We obtained Massachusetts daily temperature data from 397 different sites resulting in 50 to 190 daily measurements, from four different data sources: NCDC, EPA, Weatherbug, and Weatherunderground. Land use, elevation and census data were obtained from the National Land Cover Database 2001 provided by USGS and the Massachusetts Geographic Information System. The prediction model for daily temperature at an address included daily intercepts and smooth functions of space, season specific smooth functions of space, distance to coastline, elevation and landuse. Mortality data was obtained from Department of Public Health for Eastern Massachusetts. Residences of the 125,409 out-of-hospital-deaths were geocoded. A time stratified case-crossover analysis was conducted with estimated temperatures at place of residence as exposure variable. We examined individual and contextual covariates as modifiers of the effect of temperature, to examine questions of susceptibility. We compared our results using temperature at Logan airport as exposure variable. Results: For daily maximum summer temperature at place of residence we estimated an increase of 2% (95% CI 0.1–3.8%) deaths per 7°C. Compared to this the association of mortality with temperature at Logan airport of 3% (95% CI 1.1–5.6) was somewhat larger. After stratifying by location specific average temperature level we observed higher effects for subjects with residence at locations with more moderate temperatures. Conclusion: A rise in summer temperature was associated with a higher risk in mortality, which may be modified by mean temperature level.