Papers Winter mortality and cold stress in Yekaterinburg, Russia: interview survey BMJ: first published as 10.1136/bmj.316.7130.514 on 14 February 1998. Downloaded from G C Donaldson, V E Tchernjavskii, S P Ermakov, K Bucher, W R Keatinge Department of Abstract the increase in mortality seems to be associated with Physiology, Basic cold stress (personal exposure to cold); time series Medical Sciences, Objectives: To evaluate how mortality and protective Queen Mary and analyses have shown that mortality increases within 24 Westfield College, measures against exposure to cold change as hours of a fall in temperature.4 Deaths from thrombo- University of temperatures fall between October and March in a sis, which account for most of the excess mortality London, London region of Russia with a mean winter temperature E1 4NS associated with cold, are probably caused by haemo- − o G C Donaldson, below 6 C. concentration resulting from cold stress (general expo- senior research Design: Interview to assess factors associated with sure to cold)56 and an increase in plasma fibrinogen associate cold stress both indoors and outdoors, to measure W R Keatinge, concentrations as a result of an acute response to res- temperatures in living room, and to survey unheated 78 emeritus professor of piratory infections. The increase in mortality that physiology rooms. occurs with each fall of 1°C in outdoor temperature is Russian Ministry of Setting: Sverdlovsk Oblast (district), Yekaterinburg, smaller in areas of Europe where houses are warmer Health, Russia. 11 Dobrolubova and more clothing is worn outdoors at a given outdoor Subjects: Residents aged 50-59 and 65-74 living 9 Street, Moscow temperature. However, it is unclear whether protec- 127254, Russia within approximately 140 km of Yekaterinburg in tion against cooling of the body surface alone can V E Tchernjavskii, Sverdlovsk Oblast. Survey of sample of 1000 residents entirely prevent higher mortality in winter. This deputy director, public equally distributed by sex and age groups. health institute protection would not be effective if, for example, local Main outcome measures: Regression analysis was SPErmakov, cooling of the respiratory tract caused by breathing principal researcher used to relate data on indoor heating and cold air was an important factor in the deaths. temperatures, the amount of clothing worn, the Dezemat This paper reports patterns of winter mortality and Biosynoptik der amount of physical activity, and shivering while various strategies for protection against cold in the Zentralen Medizin- outside, to outdoor temperature; results were Meteorologischen Yekaterinburg region of Russia, 850 miles east and Forschungsstelle compared with mortality patterns for ischaemic heart slightly north of Moscow. It is a densely populated des Deutschen disease, cerebrovascular disease, respiratory disease, region, where many people spend substantial time out- Wetterdienstes, and mortality from all causes. Stefan Maier doors. The mean winter temperature is − 6.8°C, lower Strasse 4, 7800 Results: As mean daily temperatures fell to 0°C the than that in any part of western Europe (fig 1). Our Freiburg 1, amount of clothing worn outdoors increased, physical objective was to evaluate whether the type and amount Germany activity while outdoors became more continuous, and K Bucher, of outdoor clothing worn and the amount of physical head only 11 (6.6%) of the 167 people surveyed who went activity prevented excess mortality when winter outdoors at temperatures above 0°C reported http://www.bmj.com/ Correspondence to: temperatures were similar to those found in western Professor Keatinge shivering. The mean temperature in living rooms in European regions with milder winters. w.r.keatinge@ the evening remained above 21.9°C. Mortality from qmw.ac.uk ischaemic heart disease, cerebrovascular disease, respiratory disease, and all causes did not change. As Subjects and methods BMJ 1998;316:514–8 the temperature fell below 0°C the number of items of Subjects and survey of lifestyle clothing worn plateaued at 16.0 and the number of Subjects were selected for interview by a two stage proc- layers at 3.7. With regression analysis, shivering 11 ess. Primary sampling areas were designated from cen- on 28 September 2021 by guest. Protected copyright. outdoors was found to increase progressively to sus data and selected to be representative of population − 34.6% (P < 0.001) of excursions at 25°C, and density and composition of social groups. Each mortality (after declining slightly) rose progressively interviewer was allocated a sampling area each day. To (all cause mortality rose by 1.15% for each 1°C drop in temperature from 0°C to − 29.6°C, 95% confidence interval 0.97% to 1.32%). 94.2% of bedrooms were directly heated, and evening temperatures in the living 60 room averaged 19.8°C even when outside No of days temperatures reached − 25°C. Conclusions: Outdoor cold stress and mortality in 40 Yekaterinburg increased only when the mean daily temperature dropped below 0°C. At temperatures down to 0°C cold stress and excess mortality were prevented by increasing the number of items of 20 clothing worn and the amount of physical activity outdoors in combination with maintaining warmth in houses. 0 -40 -20 0 20 40 Introduction Mean daily temperature (˚C) Fig 1 Numbers of days at each mean daily temperature from 1990 In cold and temperate regions mortality is minimal at to 1994 inclusive in Yekaterinburg, Russia about 18°C but rises as temperatures fall.1–3 Much of 514 BMJ VOLUME 316 14 FEBRUARY 1998 Papers prevent clustering, interviews were separated by at least four addresses and no more than two interviews were Men Women P<0.05 Age 50-59 Age 50-59 P>0.05 conducted on each street; apartment blocks were 90 considered to be streets. Samples of responses were 30 BMJ: first published as 10.1136/bmj.316.7130.514 on 14 February 1998. Downloaded from checked by telephone or by post for quality control. 80 These procedures were similar to those used in the 9 Eurowinter survey in western Europe. The survey was 70 20 conducted by a Russian-Finnish company associated 60 with Gallup and with advice from Colin McDonald (McDonald Research, Camberley). Briefing of interview- 50 10 ers and the initial interviews in Yekaterinburg were Age 65-74 Age 65-74 Daily No of deaths/million population monitored by WRK and by the survey consultant. 250 120 Interviews were conducted from the beginning of October 1995 through to the end of February 1996. 200 100 Interviews occurred on all days of the week. Interviews took place after 1700 in the main living room of the 150 80 house or apartment. Temperatures were measured to 1°C with Thermax temperature strips (Thermographic Measurements, Burton) which were placed on furni- 100 60 ture 0.5 m to 1.2 m above the floor. Interviewers then -40 -20 0 20 40 -40 -20 0 20 40 completed questionnaires. Interviewees were asked Mean daily temperature (˚C) about the duration of heating in the bedroom and liv- Fig 2 Daily numbers of deaths per million population in each sex and age group by mean ing room, the duration and number of outdoor excur- daily temperature sions, the type of clothing worn outdoors, and physical activity outdoors during the previous 24 hours; interviews were conducted in Russian. P<0.05 P>0.05 Mortality and temperature 25 Daily reports of deaths during 1990-4 were obtained for Yekaterinburg and the regions and towns of the Sverdlovsk Oblast (district) which are within about 140 20 km of Yekaterinburg; the data were reported for those aged 50-59 and 65-74 and for men and women. Census data were used to determine numbers of each 15 sex and age group. There were 192 000 men and heart disease/million population Daily No of deaths from ischaemic 258 000 women aged 50-59 and 77 000 men and 167 000 women aged 65-74. The mean daily tempera- http://www.bmj.com/ 10 ture was calculated using measurements taken every three hours in Yekaterinburg. 20 Regression analysis Regression coefficients for the number of deaths each day in relation to the mean daily temperature were esti- 15 mated for temperatures between 0°C and 18°C and for on 28 September 2021 by guest. Protected copyright. temperatures between 0°C and − 25°C; generalised lin- disease/million population ear modelling with identity link function was used and a 10 Poisson distribution was assumed.10 Regression coeffi- cients were expressed as a percentage of the estimated Daily No of deaths from cerebrovascular mortality at baseline, which was taken as 18°C. Deaths 5 were lagged on temperature by 2 days for ischaemic 8 heart disease, by 5 days for cerebrovascular disease, by 12 days for respiratory disease, by 3 days for all cause mortality; these are the delays which give maximal 6 effects.4 Deaths from influenza averaged over the 10 days before to the 10 days after each mortality were included 4 in the regression model as a second explanatory variable disease/million population to account for the effects of influenza; these effects were small as only nine deaths from influenza were recorded. 2 Daily No of deaths from respiratory For graphs, mortality data per million population were averaged for each temperature interval of 1°C. 0 Separate regressions on the mean daily tempera- -40 -20 0 20 40 tures both above and below 0°C were made by ordinary Mean daily temperature (˚C) least squares regression for the temperature in the living room. Generalised linear modelling was used for Fig 3 Daily numbers of deaths from ischaemic heart disease, cerebrovascular disease, and respiratory disease per million Poisson distributed data, and logit regression was used population by mean daily temperature for binary data.10 BMJ VOLUME 316 14 FEBRUARY 1998 515 Papers The number of layers of clothing worn was that the mortality data were collected.