Winter Kills: Excess Deaths in the Winter Months
Since extreme cold has gripped much of the Northern Hemisphere, some newspapers have been keeping a tally of the number of deaths obviously caused by extreme cold (e.g., freezing). But the BBC’s Health Correspondent, Clare Murphy, in a very timely and, in my opinion, excellent article, How cold turns up the heat on health, reminds us that many more deaths occur from chronic conditions that are exacerbated by cold weather. She also notes that, “For every degree the temperature drops below 18C, deaths in the UK go up by nearly 1.5%.”
Following is a compilation of excess deaths during the winter months (compared to what occurs on average during the rest of the year) in a number of developed countries in both the Northern and Southern Hemispheres. Unfortunately, our politicians complain about the warmth and would like to make the climate cooler if they could, even as they bemoan the costs of health care.
United States. 2001-2008
Figure 1: Average daily deaths for each month, United States, 2001-2008. Sources: 2001-2004 data from National Center for Health Statistics, DataWarehouse at http://www.cdc.gov/nchs/datawh/statab/unpubd/mortabs/gmwkIV_10.htm, and National Vital Statistics System available at http://www.cdc.gov/nchs/deaths.htm; 2005 data from Births, Marriages, Divorces, and Deaths: Provisional Data for 2006, Volume 55, Number 20, 6 pp (PHS 2007-1120); 2006 data from Births, Marriages, Divorces, and Deaths: Provisional Data for 2007. NVSR Volume 56, Number 21, 6 pp (PHS) 2008-1120; 2007-08 data from Births, Marriages, Divorces, and Deaths: Provisional Data for 2008. NVSR Volume 57, Number 19, 6 pp.
The figure above, based on data from the US National Center for Health Statistics for 2001-2008, shows that on average 7,200 Americans died each day during the months of December, January, February and March, compared to the average 6,400 who died daily during the rest of the year. In 2008, there were 108,500 “excess” deaths during the 122 days in the cold months (January to March and December; it was a leap year).
Figure 2, based on data from CANSIM for 1991-20068, shows that on average 656 Canadians died daily in January compared to 546 per day in August. In 2006, there were 5,640 excess deaths during the winter months in Canada.
Figure 2: Average daily deaths for each month, Canada, 1991-2006. Source: CANSIM (2009).
England & Wales, 1950/51-2008/09
Figure 3: Excess winter mortality, England and Wales, 1950/51–2008/09. Source: UK ONS (2009).
Figure 3 shows that despite an increase in the population of England and Wales, excess winter deaths have generally declined since the 1950s due, probably, to increased affluence, better heating and insulation, clothing and any warming (whether due to UHI or global warming). [Also, some readers may know more about this, but I believe rationing was still in force in the UK in the early 1950s. Poor nutrition would have exacerbated mortality.]
However, last winter (Dec 2008-Mar 2009), there was a remarkably large jump in the excess number of winter deaths, perhaps due to colder/damper weather and increased fuel prices. The UK’s Office of National Statistics states:
“In the winter period of December to March 2008/09 there were an estimated 36,700 more deaths in England and Wales, compared with the average for the non-winter period (see definition below). This was an increase of 49 per cent compared with the number in the previous winter 2007/08. This is the highest number of excess winter deaths since the winter of 1999/2000, when excess winter mortality was nearly a third higher than in 2008/09.”
It will be interesting to see the figures when data are available for this year.
Other Developed Countries
Figure 4: Monthly percentage variation in mortality compared to yearly average over the last years in European Mediterranean countries and other selected countries worldwide. Countries in the legend are listed according the absolute number of average deaths per day observed, in descending order. Source: Fagalas et al. (2009).
Finally, Figure 4 shows the percent variation in monthly mortality relative to annual averages for recent years in various developed countries. Notably, even Greece and Cyprus (!) have greater mortality in the winter months, even though one would not classify either of them as particularly cold places. See the Table above.
Falagas ME, Karageorgopoulos DE, Moraitis LI, Vouloumanou EK, Roussos N, Peppas G, Rafailidis PI (2009). Seasonality of mortality: the September phenomenon in Mediterranean countries. CMAJ 181(8): 484-6.