Cold-related mortality due to cardiovascular diseases, respiratory diseases and cancer: a case-crossover study.

OBJECTIVES

The aim of this study was to identify the relationship between low temperatures in winter and mortality due to cancer, cardiovascular diseases and respiratory diseases.

STUDY DESIGN

Case-crossover study.

METHODS

A case-crossover study was performed in Cantabria (northern Spain) in the years 2004-2005; 3948 deaths were included. Odds ratios were estimated using conditional logistic regression, stratified by age, sex, and delay of exposure to low temperatures.

RESULTS

There was an inverse dose-response relationship between temperature and mortality in the three causes of death studied; this result was consistent across genders and age groups. The higher OR for cancer mortality was seen on the first day of exposure (OR = 4.91; 95% CI: 1.65-13.07 in the whole population), and it decreased when exposure over several days in a row was considered; people aged 75 years or more were especially susceptible to cold temperatures (OR = 17.9; 95% CI: 2.38-134.8). Cardiovascular (OR = 2.63; 95% CI: 1.88-3.67) and respiratory mortality (OR = 2.72; 95% CI: 1.46-5.08) showed a weaker effect.

CONCLUSION

There is a striking association between the extreme cold temperatures and mortality from cancer, not previously reported, which is more remarkable in the elderly. These results could be explained by a harvesting effect in which the cold acts as a trigger of death in terminally ill patients at high risk of dying a few days or weeks later.