The effect of heat waves on mortality in susceptible groups: a cohort study of a mediterranean and a northern European City

Abstract

BackgroundClimate change is projected to increase the number and intensity of extreme weather events, for example heat waves. Heat waves have adverse health effects, especially for the elderly, since chronic diseases are more frequent in that group than in the population overall. The aim of the study was to investigate mortality during heat waves in an adult population aged 50 years or over, as well as in susceptible subgroups of that population in Rome and Stockholm during the summer periods from 2000 to 2008.MethodsWe collected daily number of deaths occurring between 15th May and 15th September each year for the population above 50 as well as the susceptible subgroups. Heat wave days were defined as two or more days exceeding the city specific 95th percentile of maximum apparent temperature (MAT). The relationship between heat waves and all-cause non-accidental mortality was investigated through time series modelling, adjusting for time trends.ResultsThe percent increase in daily mortality during heat waves as compared to normal summer days was, in the 50+ population, 22% (95% Confidence Interval (CI): 18-26%) in Rome and 8% (95% CI: 3-12%) in Stockholm. Subgroup specific increase in mortality in Rome ranged from 7% (95% CI:–17-39%) among survivors of myocardial infarction to 25% in the COPD (95% CI:9-43%) and diabetes (95% CI:14-37%) subgroups. In Stockholm the range was from 10% (95% CI: 2-19%) for congestive heart failure to 33% (95% CI: 10-61%) for the psychiatric subgroup.ConclusionsMortality during heat waves increased in both Rome and Stockholm for the 50+ population as well as in the considered subgroups. It should be evaluated if protective measures should be directed towards susceptible groups, rather than the population as a whole.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-015-0012-0) contains supplementary material, which is available to authorized users.

High Summer Temperatures and Mortality in Estonia

“…On-going climate change is predicted to result in a growing number of extreme meteorological events—such as heat waves—throughout Europe [ 1 ]. The effect of high temperatures and heat waves are already having an important impact on public health in terms of increased mortality and morbidity [ 2 – 5 ], with heightened susceptibility reported among the elderly [ 6 ] and groups with chronic disease [ 7 ]. Increasing mortality and morbidity due to elevated temperatures has been reported in Southern and Western Europe [ 2 , 3 , 5 ], Central Europe [ 8 ], and in the colder climates of Northern Europe such as in nearby Sweden and Finland [ 5 , 7 , 9 ].…”

Impact of Heat Wave Definitions on the Added Effect of Heat Waves on Cardiovascular Mortality in Beijing, China

“…Thus, a discussion on the impact of heat waves on human health problems was inevitable. The uniform effect of heat waves on mortality was assessed in many epidemiological studies across various regions [ 3 , 4 , 5 , 6 , 7 , 8 ]. However, those previous studies were focused on the independent effect of a daily high temperature, and studies about the added effect due to the duration of sustained heat for several consecutive days are still rare in Asia.…”

Vulnerability Reduction Needed to Maintain Current Burdens of Heat-Related Mortality in a Changing Climate—Magnitude and Determinants

“…A study of the future prevalence of diabetes for 21 European countries of the population aged 20–79 [ 25 ] estimated an average increase in diabetes prevalence of 13%, and an increase in the number of individuals by 23% by 2035 compared to 2013. This will likely increase the health burden from heat because people diagnosed with diabetes are more vulnerable [ 26 ]. The increase in the number of patients diagnosed with a certain disease should be treated with caution, as an increase in number (prevalence) might be due to higher survival rates [ 27 ].…”