title: Heat-related emergency hospitalizations for respiratory diseases in the Medicare population.
abstract: BACKGROUND
  The heat-related risk of hospitalization for respiratory diseases among the elderly has not been quantified in the United States on a national scale. With climate change predictions of more frequent and more intense heat waves, it is of paramount importance to quantify the health risks related to heat, especially for the most vulnerable.
  
  
  OBJECTIVE
  To estimate the risk of hospitalization for respiratory diseases associated with outdoor heat in the U.S. elderly.
  
  
  METHODS
  An observational study of approximately 12.5 million Medicare beneficiaries in 213 United States counties, January 1, 1999 to December 31, 2008. We estimate a national average relative risk of hospitalization for each 10°F (5.6°C) increase in daily outdoor temperature using Bayesian hierarchical models.
  
  
  RESULTS
  We obtained daily county-level rates of Medicare emergency respiratory hospitalizations (International Classification of Diseases, Ninth Revision, 464-466, 480-487, 490-492) in 213 U.S. counties from 1999 through 2008. Overall, each 10°F increase in daily temperature was associated with a 4.3% increase in same-day emergency hospitalizations for respiratory diseases (95% posterior interval, 3.8, 4.8%). Counties' relative risks were significantly higher in counties with cooler average summer temperatures.
  
  
  CONCLUSIONS
  We found strong evidence of an association between outdoor heat and respiratory hospitalizations in the largest population of elderly studied to date. Given projections of increasing temperatures from climate change and the increasing global prevalence of chronic pulmonary disease, the relationship between heat and respiratory morbidity is a growing concern.
authors.affiliation: Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: G Brooke
authors.initials: GB
authors.lastname: Anderson
authors.forename: Francesca
authors.initials: F
authors.lastname: Dominici
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Bell
authors.forename: Roger D
authors.initials: RD
authors.lastname: Peng
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D004632:Emergency Medical Services / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D006278:Medicare; D012120:Respiration Disorders / Q000453:epidemiology*; D012306:Risk; D014481:United States / Q000453:epidemiology