title: The effect of heat waves on mortality in susceptible groups: a cohort study of a mediterranean and a northern European City.
abstract: BACKGROUND
  Climate 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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  Mortality 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.
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, Umeå University, Umeå, Sweden. daniel.astrom@envmed.umu.se.
authors.forename: Daniel
authors.initials: D
authors.lastname: Oudin Åström
authors.affiliation: Department of Epidemiology, Lazio Regional Health Service, Rome, Italy. p.schifano@deplazio.it.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Schifano
authors.affiliation: Department of Epidemiology, Lazio Regional Health Service, Rome, Italy. f.asta@deplazio.it.
authors.forename: Federica
authors.initials: F
authors.lastname: Asta
authors.affiliation: Department of Epidemiology, Lazio Regional Health Service, Rome, Italy. a.lallo@deplazio.it.
authors.forename: Adele
authors.initials: A
authors.lastname: Lallo
authors.affiliation: Department of Epidemiology, Lazio Regional Health Service, Rome, Italy. p.michelozzi@deplazio.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Michelozzi
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Epidemiology and Global Health, Umeå University, Umeå, Sweden. joacim.rocklov@envmed.umu.se.
authors.forename: Joacim
authors.initials: J
authors.lastname: Rocklöv
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, Umeå University, Umeå, Sweden. bertil.forsberg@envmed.umu.se.
authors.forename: Bertil
authors.initials: B
authors.lastname: Forsberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002947:Cities / Q000453:epidemiology; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000209:etiology / Q000401:mortality; D055874:Extreme Heat / Q000009:adverse effects*; D005260:Female; D006333:Heart Failure / Q000209:etiology / Q000401:mortality; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000209:etiology / Q000401:mortality; D008875:Middle Aged; D009026:Mortality; D009203:Myocardial Infarction / Q000453:epidemiology / Q000209:etiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000401:mortality; D012306:Risk; D012384:Rome / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology