Excess cardiovascular mortality associated with cold spells in the Czech Republic

Jan Kysely,Jan Kyncl,Lucie Pokorna,Bohumir Kriz

doi:10.1186/1471-2458-9-19

Jan Kysely, Jan Kyncl + Show 2 more

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https://doi.org/10.1186/1471-2458-9-19

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Abstract

BackgroundThe association between cardiovascular mortality and winter cold spells was evaluated in the population of the Czech Republic over 21-yr period 1986–2006. No comprehensive study on cold-related mortality in central Europe has been carried out despite the fact that cold air invasions are more frequent and severe in this region than in western and southern Europe.MethodsCold spells were defined as periods of days on which air temperature does not exceed -3.5°C. Days on which mortality was affected by epidemics of influenza/acute respiratory infections were identified and omitted from the analysis. Excess cardiovascular mortality was determined after the long-term changes and the seasonal cycle in mortality had been removed. Excess mortality during and after cold spells was examined in individual age groups and genders.ResultsCold spells were associated with positive mean excess cardiovascular mortality in all age groups (25–59, 60–69, 70–79 and 80+ years) and in both men and women. The relative mortality effects were most pronounced and most direct in middle-aged men (25–59 years), which contrasts with majority of studies on cold-related mortality in other regions. The estimated excess mortality during the severe cold spells in January 1987 (+274 cardiovascular deaths) is comparable to that attributed to the most severe heat wave in this region in 1994.ConclusionThe results show that cold stress has a considerable impact on mortality in central Europe, representing a public health threat of an importance similar to heat waves. The elevated mortality risks in men aged 25–59 years may be related to occupational exposure of large numbers of men working outdoors in winter. Early warnings and preventive measures based on weather forecast and targeted on the susceptible parts of the population may help mitigate the effects of cold spells and save lives.

Highlights

The association between cardiovascular mortality and winter cold spells was evaluated in the population of the Czech Republic over 21-yr period 1986–2006
Cold spells with at least one day on which mortality was affected by an epidemic of influenza/ARI were excluded from the analysis
Basic features of excess CVD mortality associated with cold spells The mean relative excess CVD mortality associated with cold spells was positive for all age groups and in both men and women (Table 1)

Summary

Introduction

The association between cardiovascular mortality and winter cold spells was evaluated in the population of the Czech Republic over 21-yr period 1986–2006. In mid-latitudes, the most direct effects of weather on human health are observed during and after summer heat waves [1,2,3,4,5,6,7,8]. The lags between cold weather and its impacts on mortality are usually longer (about a week compared with 0–1 days for heat-related mortality), and the relationship is less direct, geographically more variable, and it may be partly confounded by other factors that strongly influence mortality in winter (e.g. influenza epidemics and outbreaks of other acute respiratory infections). A harvesting effect often occurs for several days, but cold spells may rise levels of mortality for several weeks and no subsequent declines of mortality rates below expected levels have been observed [16]

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