Excess Mortality during heat waves and cold spells in Moscow, Russia

¹ Institute of Forecasting, Russian Federation

^* To whom correspondence should be addressed. E-mail: dshap{at}newmail.ru.

Accepted 18 January 2008

	Abstract

Objectives: To estimate excess mortality during heat waves and cold spells, and to identify vulnerable population groups, by age and cause of death.

Methods: The authors analyzed daily mortality from all non-accidental causes, cardio-vascular and respiratory mortality among all ages and in age group 75+, between January 2000 and February 2006 in Moscow, Russia. Mortality and displaced mortality during cold and heat waves were estimated using independent samples t-tests.

Results: Several discrete weather events during the period 2000-2006 were analyzed. Cumulative excess non-accidental mortality during the heatwave of 2001 was 33% (95% CI 20 to 46), or about 1200 additional deaths, with the share of short-term displaced mortality only about 10%. Mortality from coronary heart disease increased by 32% (16 to 48); cerebrovascular mortality increased by 51% (29 to 73), and respiratory mortality increased by 80% (57 to 101). In the age group 75+, corresponding mortality increments were consistently higher for all studied categories except respiratory deaths. An estimated 560 extra deaths were observed during the three heat waves of 2002, when non-accidental mortality increased by 8.5%, 7.8% and 6.1%, respectively. About 40% of these deaths were brought forward by only several days, thus bringing net mortality change down to 3.2% (0.8 to 5.5). The cumulative effects of the two cold spells of 2006 on mortality were significant only in the age group 75+, for which average daily mortality from all non-accidental causes increased by 9.9% (8.0 to 12) and 8.9% (6.7 to 11), resulting in 370 extra deaths; there was also a significant increase in coronary disease mortality and cerebrovascular mortality.

Conclusions: This study confirms that daily mortality does increase in Moscow during heatwaves and cold spells. A large proportion of excess deaths during heatwaves occur only a short time earlier than they would otherwise have done, but harvesting, or short-term mortality displacement, may be less significant for longer periods of sustained heat stress.