Cold exposure and winter mortality from ischaemic heart disease, cerebrovascular disease, respiratory disease, and all causes in warm and cold regions of Europe. The Eurowinter Group.

BACKGROUND

Differences in baseline mortality, age structure, and influenza epidemics confound comparisons of cold-related increases in mortality between regions with different climates. The Eurowinter study aimed to assess whether increases in mortality per 1 degree C fall in temperature differ in various European regions and to relate any differences to usual winter climate and measures to protect against cold.

METHODS

Percentage increases in deaths per day per 1 degree C fall in temperature below 18 degrees C (indices of cold-related mortality) were estimated by generalised linear modelling. We assessed protective factors by surveys and adjusted by regression to 7 degrees C outdoor temperature. Cause-specific data gathered from 1988 to 1992 were analysed by multiple regression for men and women aged 50-59 and 65-74 in north Finland, south Finland, Baden-Württemburg, the Netherlands, London, and north Italy (24 groups). We used a similar method to analyse 1992 data in Athens and Palermo.

FINDINGS

The percentage increases in all-cause mortality per 1 degree C fall in temperature below 18 degrees C were greater in warmer regions than in colder regions (eg, Athens 2.15% [95% CI 1.20-3.10] vs south Finland 0.27% [0.15-0.40]). At an outdoor temperature of 7 degrees C, the mean living-room temperature was 19.2 degrees C in Athens and 21.7 degrees C in south Finland; 13% and 72% of people in these regions, respectively, wore hats when outdoors at 7 degrees C. Multiple regression analyses (with allowance for sex and age, in the six regions with full data) showed that high indices of cold-related mortality were associated with high mean winter temperatures, low living-room temperatures, limited bedroom heating, low proportions of people wearing hats, gloves, and anoraks, and inactivity and shivering when outdoors at 7 degrees C (p < 0.01 for all-cause mortality and respiratory mortality; p > 0.05 for mortality from ischaemic heart disease and cerebrovascular disease).

INTERPRETATION

Mortality increased to a greater extent with given fall of temperature in regions with warm winters, in populations with cooler homes, and among people who wore fewer clothes and were less active outdoors.