CONTEXT: @entity301 is the major cause of mortality in the United States. Factors associated with coronary risk are important to identify. Coronary mortality is greater during the winter months. OBJECTIVE: To investigate whether declining coronary mortality has been accompanied by a change in the seasonal pattern and to investigate the hypothesis that diminishing exposures to environmental cold and heat have affected the seasonal pattern. DESIGN: We used published data on coronary mortality by year to evaluate the time trend in the seasonal pattern. We fit a sine curve to the monthly frequency of @entity204 in each year and examined the trend over time in the ratio of the peak to the trough of the curve. SETTING: We used monthly coronary @entity204 in the United States from 1937 through 1991. Deaths by cause and month were not available by geographic area within the United States, but we were able to examine total monthly @entity204 in 2 regions with contrasting climates, New England and the South. OUTCOME MEASURES: We used the yearly peak-to-trough ratio as our primary outcome and assessed its trend over time by linear regression. We also depicted the time trends using polynomial smoothing. RESULTS: The peak-to-trough ratio diminished by about 2% per year until around 1970, when the trend reversed. In New England, the decline was steeper than in the South, as measured from all @entity204 . CONCLUSION: Seasonal patterns in coronary mortality in the United States have changed with time. These changes are compatible with the gradual expansion of adequate heating and the subsequent increased use of air-conditioning. Microclimatic influences on coronary mortality could explain in part the socioeconomic gradient of @entity65 .

Changing seasonality of mortality from XXXX .

@entity204 :: ('MESH:D003643', 'Disease') :: ['deaths'] @entity65 :: ('MESH:D002318', 'Disease') :: ['cardiovascular mortality'] @entity301 :: ('MESH:D003327', 'Disease') :: ['Coronary heart disease']
@entity301 :: (MESH:D003327,Disease) :: ['coronary heart disease']
