title: Geographic variability in hospital admission rates for respiratory disease among the elderly in the United States.
abstract: BACKGROUND
  The elderly represent a susceptible subpopulation that experiences disproportionate levels of morbidity and mortality from respiratory disease. As a consequence, they are frequently hospitalized for these conditions. Evaluating the geographic distributions of these hospital admissions can provide useful insights concerning patterns in incidence and medical care for respiratory diseases.
  
  
  METHODS
  All hospital admissions for pneumonia, acute respiratory infections, asthma, and chronic obstructive pulmonary disease from the United States for a 6-year period (1984 through 1989) were identified using Medicare admissions records. Age-, race-, and sex-standardized annual admission rates were calculated for each county and spatial clustering of disease specific rates was evaluated using Moran's I statistic. Ecologic analyses were conducted using multiple regression procedures with county-specific measures of average annual temperature, average income, household crowding, median educational level, population density, physicians per capita, and hospital beds per capita together with surrogate measures of cigarette consumption and occupational exposures as predictor variables.
  
  
  RESULTS
  Hospital admission rates in the elderly for all four categories of respiratory disease showed marked regional elevations (p < 0.0001), particularly in the southeast and the northern plains states. Low median education level, low per capita income, and household crowding were all associated with elevated hospital admission rates. Surrogate measures of cigarette consumption were strongly associated with hospital admissions in all four disease groups. Hospital beds per capita demonstrated positive associations with hospital admissions, but the number of physicians per capita exhibited consistent inverse relationships with hospital admissions.
  
  
  CONCLUSIONS
  Hospital admission rates for respiratory diseases among the elderly show marked geographic variation and are associated with regional indicators of socioeconomic status, availability of medical resources, occupational lung disease rates, and smoking.
authors.affiliation: Division of Epidemiology, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: R D
authors.initials: RD
authors.lastname: Morris
authors.forename: R L
authors.initials: RL
authors.lastname: Munasinghe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003710:Demography; D005260:Female; D006297:Health Services Accessibility / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D010343:Patient Admission / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D012044:Regression Analysis; D012140:Respiratory Tract Diseases / Q000453:epidemiology*; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology