Temperature and cardiovascular deaths in the US elderly: changes over time.

BACKGROUND

Short-term changes in temperature have been associated with cardiovascular deaths. This study examines changes in this association over time among the US elderly.

METHODS

Daily cardiovascular mortality counts from 107 cities in the US National Morbidity and Mortality Air Pollution Study were regressed against daily temperature using the case-crossover method. Estimates were averaged by time and season using a meta-analysis.

RESULTS

In summer 1987 the average increase in cardiovascular deaths due to a 10 degrees F increase in temperature was 4.7%. By summer 2000, the risk with higher temperature had disappeared (-0.4%). In contrast, an increase in temperature in fall, winter and spring was associated with a decrease in deaths, and this decrease remained constant over time.

CONCLUSIONS

Heat-related cardiovascular deaths in the elderly have declined over time, probably due to increased use of air conditioning, while increased risks with cold-related temperature persist.