Cold-related cardiac mortality in King County, Washington, USA 1980-2001

Background: Studies have shown that cardiac deaths increase during the winter months and that death rates can be tightly predicted from temperature rather than other atmospheric phenomena such as barometric pressure, humidity, or pollution. Aim: The object of this study is to examine the possible relationship between temperature and cardiac death rates in King County, Washington, USA and suggest possible public health measures that can decrease the number of cardiac deaths associated with cold exposure. Subjects and methods: State death records show that 621 25 total out-of-hospital cardiac-related deaths among persons 55 years and older occurred in King County between 1980 and 2001. We use Poisson regression to examine the association between same-day daily average temperature and death rate after adjusting for seasonal effects. Results: We identified a significant negative association between daily average temperature and cardiac mortality among persons over 55 years of age. A 5 degrees C increase in temperature was associated with a decrease in death rate by a factor of 0.971 (95% CI: 0.961, 0.982). Conclusion: Cold temperatures may be an important triggering factor in bringing on the onset of life-threatening cardiac events, even in regions with relatively mild winters. Public health efforts stressing cold exposure while out of doors may play a prominent role in encouraging a reduction in cold stress, especially among seniors and those already at higher risk of cardiac death.