Background
Ischaemic heart disease is the leading cause of death in the British Isles, followed by cerebrovascular and respiratory diseases.  All three of these purveyors of death display clear winter peaks of mortality related to the cold temperatures of that time of year (Fleming et al., 2000; Gemmell et al., 2000; Lawlor et al., 2000; Grech et al., 2001; van Rossum et al., 2001; Eccles, 2002; Law et al., 2002; Verlato et al., 2002).  McGregor et al. explore this relationship in more detail for the foremost of the "big three" killers, which has been estimated to cost the UK economy some £10 billion every single year (British Heart Foundation, 2000).

What was done
For the period 1974-1999, data on ischaemic heart disease (IHD) and temperature for five English counties aligned on a north-south transect (Tyne and Wear, West Yorkshire, Greater Manchester, West Midlands, and Hampshire) were analyzed in such a way as to reveal any relationships that might exist between the two parameters.

What was learned
The health researchers report that "the seasonal cycles of temperature and mortality are inversely related," and that "the first harmonic accounts for at least 85% (significant at the 0.01 level) of the variance of temperature and mortality at both the climatological and yearly time scales."  They also note that "years with an exaggerated mortality peak are associated with years characterized by strong temperature seasonality," and that "the timing of the annual mortality peak is positively associated with the timing of the lowest temperatures."

What it means
Winter cold in the British Isles extracts a heavy toll in terms of deaths from ischaemic heart disease and their attendant economic costs, the reason being, in the words of McGregor et al., that "frequent exposure to cold causes a rise in IHD risk factors (Lloyd, 1991) through increasing blood pressure and viscosity, vasoconstriction, heart rate and angina (Morgan and Moran, 1997)."  Hence, with global warming making its biggest impact on daily minimum temperatures in the winter, its occurrence would appear to be good medicine indeed for Britain and beyond.

References
British Heart Foundation.  2000.  Coronary Heart Disease Statistics: British Heart Foundation Statistics Database 2000.  British Heart Foundation, Oxford, UK.

Eccles, R.  2002.  An explanation for the seasonality of acute upper respiratory tract viral infections.  Acta Oto-Laryngologica 122: 183-191.

Fleming, D.M., Cross, K.W., Sunderland, R. and Ross, A.M.  2000.  Comparison of the seasonal patterns of asthma identified in general practitioner episodes, hospital admissions, and deaths.  Thorax 55: 662-665.

Gemmell, I., McLoone, P., Boddy, F.A., Dickinson, G.J. and Watt, G.C.M.  2000.  Seasonal variations in mortality in Scotland.  International Journal of Epidemiology 29: 274-279.

Grech, V., Aquilina, O. and Pace, J.  2001.  Gender differences in seasonality of acute myocardial infarction admissions and mortality in a population-based study.  Journal of Epidemiology and Community Health 55: 147-148.

Law, B.J., Carbonell-Estrany, X. and Simoes, E.A.F.  2002.  An update on respiratory syncytial virus epidemiology: a developed country perspective.  Respiratory Medicine Supplement B 96: S1-S7.

Lawlor, D.A., Harvey, D. and Dews, H.G.  2000.  Investigation of the association between excess winter mortality and socioeconomic deprivation.  Journal of Public Health Medicine 22: 176-181.

Lloyd, E.L.  1991.  The role of cold in ischaemic heart disease: a review.  Public Health 105: 205-215.

Morgan, M.D. and Moran, J.M.  1997.  Weather and People.  Prentice Hall, Englewood Cliffs, NJ, USA.

van Rossum, C.T.M., Shipley, M.J., Hemingway, H., Grobbee, D.E., Mackenbach, J.P. and Marmot, M.G.  2001.  Seasonal variation in cause-specific mortality: are there high-risk groups?  25-year follow-up of civil servants from the first Whitehall study.  International Journal of Epidemiology 30: 1109-1116.

Verlato, G., Calabrese, R. and De Marco, R.  2002.  Correlation between asthma and climate in the European Community Respiratory Health Survey.  Archives of Environmental Health 57: 48-52.