What was done
The authors analyzed data from the World Health Organization (WHO) Collaborative Study of CVD [cardiovascular disease] and Steroid Hormone Contraception (WHO, 1995) to determine the effects of monthly mean temperature on rates of hospitalization for arterial stroke and acute myocardial infarction (AMI) among young women aged 15-49 from seventeen different countries in Africa, Asia, Europe, Latin America and the Caribbean.

What was learned
Chang et al. report that "among young women from 17 countries, the rate of hospitalized AMI, and to a lesser extent stroke, was higher with lower mean environmental air temperature."  More specifically, they say that "on average, a 5°C reduction in mean air temperature was associated with a 7 and 12% increase in the expected hospitalization rates of stroke and AMI, respectively."  They also note that "the findings of an inverse association between mean air temperature and hospitalization rate of AMI in this study are in agreement with several other studies," citing those of Douglas et al. (1990), Douglas et al. (1991), Mackenbach et al. (1992), Douglas et al. (1995), Seto et al. (1998), Danet et al. (1999) and Crawford et al. (2003).  Last of all, they note that "lagging the effects of temperature suggested that these effects were relatively acute, within a period of a month."

What it means
Climate alarmists ring all sorts of alarm bells when episodic heat waves lead to the deaths of people who often would have died in the short term anyway [see our reviews of studies that evaluate this harvesting effect of heat waves, whereby unseasonable warmth typically leads to short-term increases in mortality that are followed by declines in deaths, many of which may be found under the heading Health Effects (Temperature - Hot Weather) in our Subject Index].  They seem never to mention, however, that vastly larger numbers of young to middle-age people (what Chang et al. repeatedly refer to as young women in their study), either die or suffer the debilitating consequences of various cardiovascular diseases as a result of the routine occurrence of normal cold temperatures each year.  That they thus hyperventilate about the less significant and ignore the more significant says much about the sincerity of what one might call their episodic remorse, unless, of course, they really are ignorant of these facts.

References
Crawford, V.L.S., McCann, M. and Stout, R.W.  2003.  Changes in seasonal deaths from myocardial infarction.  Quarterly Journal of Medicine 96: 45-52.

Danet, S., Richard, F., Montaye, M., Beauchant, S., Lemaire, B., Graux, C., Cottel, D., Marecaux, N. and Amouyel, P.  1999.  Unhealthy effects of atmospheric temperature and pressure on the occurrence of myocardial infarction and coronary deaths - a 10-year survey - the Lille WHO-MONICA Project.  Circulation 100: E1-7.

Douglas, A.S., Allan, T.M. and Rawles, J.M.  1991.  Composition of seasonality of disease.  Scottish Medical Journal 36: 76-82.

Douglas, A.S., Dunnigan, M.G., Allan, T.M. and Rawles, J.M.  1995.  Seasonal variation in coronary heart disease in Scotland.  Journal of Epidemiology and Community Health 49: 575-582.

Douglas, A.S., Russell, D. and Allan, T.M.  1990.  Seasonal, regional and secular variations of cardiovascular and cerebrovascular mortality in New Zealand.  Australia and New Zealand Journal of Medicine 20: 669-676.

Mackenbach, J.P., Kunst, A.E. and Looman, C.W.N.  1992.  Seasonal variation in mortality in the Netherlands.  Journal of Epidemiology and Community Health 46: 261-265.

Seto, T.B., Mittleman, M.A., Davis, R.B., Taira, D.A. and Kawachi, I.  1998.  Seasonal variation in coronary artery disease mortality in Hawaii: observational study.  British Medical Journal 16: 1946-47.

WHO.  1995.  WHO Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception. A multinational case-control study of cardiovascular disease and steroid hormone contraceptives: description and validation of methods.  Journal of Clinical Epidemiology 48: 1513-1547.