title: Using the ecology model to describe the impact of asthma on patterns of health care.
abstract: BACKGROUND
  Asthma changes both the volume and patterns of healthcare of affected people. Most studies of asthma health care utilization have been done in selected insured populations or in a single site such as the emergency department. Asthma is an ambulatory sensitive care condition making it important to understand the relationship between care in all sites across the health service spectrum. Asthma is also more common in people with fewer economic resources making it important to include people across all types of insurance and no insurance categories. The ecology of medical care model may provide a useful framework to describe the use of health services in people with asthma compared to those without asthma and identify subgroups with apparent gaps in care.
  
  
  METHODS
  This is a case-control study using the 1999 U.S. Medical Expenditure Panel Survey. Cases are school-aged children (6 to 17 years) and young adults (18 to 44 years) with self-reported asthma. Controls are from the same age groups who have no self-reported asthma. Descriptive analyses and risk ratios are placed within the ecology of medical care model and used to describe and compare the healthcare contact of cases and controls across multiple settings.
  
  
  RESULTS
  In 1999, the presence of asthma significantly increased the likelihood of an ambulatory care visit by 20 to 30% and more than doubled the likelihood of making one or more visits to the emergency department (ED). Yet, 18.8% of children and 14.5% of adults with asthma (over a million Americans) had no ambulatory care visits for asthma. About one in 20 to 35 people with asthma (5.2% of children and 3.6% of adults) were seen in the ED or hospital but had no prior or follow-up ambulatory care visits. These Americans were more likely to be uninsured, have no usual source of care and live in metropolitan areas.
  
  
  CONCLUSIONS
  The ecology model confirmed that having asthma changes the likelihood and pattern of care for Americans. More importantly, the ecology model identified a subgroup with asthma who sought only emergent or hospital services.
authors.affiliation: Department of Research, Olmsted Medical Center, Rochester, MN 55904, USA. yawnx002@umn.edu
authors.forename: Barbara P
authors.initials: BP
authors.lastname: Yawn
authors.forename: George E
authors.initials: GE
authors.lastname: Fryer
authors.forename: Robert L
authors.initials: RL
authors.lastname: Phillips
authors.forename: Susan M
authors.initials: SM
authors.lastname: Dovey
authors.forename: David
authors.initials: D
authors.lastname: Lanier
authors.forename: Larry A
authors.initials: LA
authors.lastname: Green
mesh_terms: D000328:Adult; D001249:Asthma / Q000150:complications* / Q000628:therapy*; D016022:Case-Control Studies; D002648:Child; D004463:Ecology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005102:Health Expenditures / Q000706:statistics & numerical data; D006296:Health Services / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D014481:United States