[Seasonal variation of mortality from cerebro-cardiovascular diseases--effect of ambient temperature on death].

A study to clarify the relationship between seasonal variations in mortality from cerebro-cardiovascular diseases and ambient temperature (maximum/minimum temperature and daily range) was performed using time series analysis, and the role of ambient temperature as an associated factor in cerebro-cardiovascular disease caused death was discussed. The following results were obtained: 1) The seasonality factor associated with the monthly variation for mortality was of greater magnitude for heart diseases more than for cerebral diseases. There was a tendency for mortality from cardiac diseases to decline gradually from February/March to July/August, and to increase in October/November, with a maximum peak in the curve of seasonal variation observed in January/February. 2) The seasonal factor associated with maximum/minimum temperature and daily temperature range showed a stable variation in magnitude from January to December, with temperatures displaying a single peak in August. Daily temperature range was lowest during summer and highest during the late fall, winter or early spring. 3) A statistically significant negative correlation was seen between mortality from cerebro-cardiovascular diseases and seasonality and temperature, while a positive correlation was seen between mortality and daily temperature range, suggesting that low environmental temperatures may operate indirectly as a factor that affects cerebro-cardiovascular disease mortality.