Cold periods and coronary events: an analysis of populations worldwide
- Adrian G Barnett1,
- Annette J Dobson1,
- Patrick McElduff2,
- Veikko Salomaa3,
- Kari Kuulasmaa3,
- Susana Sans4,
- for the WHO MONICA project*
- 1School of Population Health, University of Queensland, Herston, Australia
- 2The Medical School, University of Manchester, Manchester, UK
- 3KTL-NPHI, Department of Epidemiology, Helsinki, Finland
- 4Institute of Health Studies, Department of Health, Barcelona, Spain
- Correspondence to: Dr A G Barnett School of Population Health, University of Queensland, Herston, QLD 4006, Australia;
- Accepted 1 December 2004
Study objective: To investigate the association between cold periods and coronary events, and the extent to which climate, sex, age, and previous cardiac history increase risk during cold weather.
Design: A hierarchical analyses of populations from the World Health Organisation’s MONICA project.
Setting: Twenty four populations from the WHO’s MONICA project, a 21 country register made between 1980 and 1995.
Patients: People aged 35–64 years who had a coronary event.
Main results: Daily rates of coronary events were correlated with the average temperature over the current and previous three days. In cold periods, coronary event rates increased more in populations living in warm climates than in populations living in cold climates, where the increases were slight. The increase was greater in women than in men, especially in warm climates. On average, the odds for women having an event in the cold periods were 1.07 higher than the odds for men (95% posterior interval: 1.03 to 1.11). The effects of cold periods were similar in those with and without a history of a previous myocardial infarction.
Conclusions: Rates of coronary events increased during comparatively cold periods, especially in warm climates. The smaller increases in colder climates suggest that some events in warmer climates are preventable. It is suggested that people living in warm climates, particularly women, should keep warm on cold days.
Funding: the MONICA centres were funded by regional and national governments, research councils, charities, and other local sources. Central coordination was the responsibility of the World Health Organisation (WHO), assisted by the MONICA Data Centre (MDC) at the National Public Health Institute (KTL) in Helsinki. Initial funding for the MDC came from WHO, KTL, and NHLBI (USA) and later from two BIOMED grants from the European Commission. The latter supported completion of the project, along with grants from pharmaceutical companies and medical charities. This work received funding by the National Health and Medical Research Council of Australia (grant numbers 100954 and 252834).
Competing interests: none declared.
Ethics approval: MONICA investigators had to satisfy the local requirements for ethical research in each population in which they worked.19