Excess winter mortality from ischaemic heart disease and stroke during colder and warmer years in Israel

Most data on winter excess mortality from cardiovascular diseasehave been reported from countries with large seasonal temperaturevariations. In this study, the contribution of environmentaltemperature to ischaemic heart disease (IHD) and stroke mortalitywas evaluated in a country with relatively small variationsin seasonal temperature. The association between monthly temperatureand cause-specific monthly proportion of annual mortality wasstudied in the population of Israel aged 45 years and over forthe period 1976-85. Population size in this group averaged nearly1 million people during the study period, and about 40% of alldeaths were due to IHD or stroke. For men, IHD mortality was51% higher and stroke mortality 48% higher in mid-winter thanin mid-summer; for women the respective figures were 48% and40%. In cosinor analysis for months above and below the medianminimum temperature, it was shown that excess mortality in winterwas greater in years below the median minimum temperature inalmost all age-sex categories. In partial correlation analysis,most of the variation in IHD and stroke mortality was explainedby variation in minimum monthly temperature. These findingsstrongly support the role of environmental temperature in excesswinter mortality from cardiovascular disease over a wide agerange, and efforts should be directed at identifying interventionmeasures which could significantly reduce the incidence of prematuremortality.