title: Impact of underuse, overuse, and discretionary use on geographic variation in the use of coronary angiography after acute myocardial infarction.
abstract: BACKGROUND
  Geographic variation in the use of medical procedures has been well documented. However, it is not known whether this variation is due to differences in use when procedures are indicated, discretionary, or contraindicated.
  
  
  OBJECTIVE
  To examine whether use of coronary angiography after acute myocardial infarction (AMI) according to appropriateness criteria varied across geographic regions and whether underuse, overuse, or discretionary use accounted for variation in overall use.
  
  
  METHODS
  Retrospective cohort study using data from the Cooperative Cardiovascular Project.
  
  
  METHODS
  Ninety-five hospital referral regions.
  
  
  METHODS
  There were 44,294 Medicare patients hospitalized with AMI during 1994 or 1995, classified according to appropriateness for angiography.
  
  
  METHODS
  Variation in use of angiography, as measured by the difference between high and low rates of use across regions.
  
  
  RESULTS
  Across regions, variation in the use of angiography was similar for indications judged necessary; appropriate, but not necessary; or uncertain. Variation was lowest for indications judged unsuitable (difference between high rate and low rate across regions = 16.3%; 95% CI = 12.6%; 20.6%). The primary cause of variation in the overall rate of angiography was due to use for indications judged appropriate, but not necessary or uncertain. When variation associated with these indications was accounted for, the difference between the resulting high and low overall rates was 10.8% (9.4%, 12.4%). In contrast, variation in the overall rate remained high when underuse in necessary situations or overuse in unsuitable situations was accounted for.
  
  
  CONCLUSIONS
  Across regions, practice was more similar for patients categorized unsuitable for angiography than for patients with other indications. Variation in overall use of angiography appeared to be driven by utilization for discretionary indications rather than by underuse or overuse. If equivalent rates across geographic areas are judged desirable, then greater effort must be directed toward defining care for patients with discretionary indications.
authors.affiliation: Department of Health Care Policy, Harvard Medical School, Boston MA 02115-5899, USA. guadagnoli@hcp.med.harvard.edu
authors.forename: E
authors.initials: E
authors.lastname: Guadagnoli
authors.forename: M B
authors.initials: MB
authors.lastname: Landrum
authors.forename: S L
authors.initials: SL
authors.lastname: Normand
authors.forename: J Z
authors.initials: JZ
authors.lastname: Ayanian
authors.forename: P
authors.initials: P
authors.lastname: Garg
authors.forename: P J
authors.initials: PJ
authors.lastname: Hauptman
authors.forename: T J
authors.initials: TJ
authors.lastname: Ryan
authors.forename: B J
authors.initials: BJ
authors.lastname: McNeil
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014487:Centers for Medicare and Medicaid Services, U.S. / Q000706:statistics & numerical data; D017023:Coronary Angiography / Q000592:standards / Q000706:statistics & numerical data*; D005260:Female; D019983:Guideline Adherence / Q000592:standards / Q000706:statistics & numerical data; D006300:Health Services Misuse / Q000706:statistics & numerical data*; D006302:Health Services Research; D006801:Humans; D007344:Insurance Claim Reporting / Q000706:statistics & numerical data; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification / Q000000981:diagnostic imaging*; D018579:Patient Selection; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000592:standards / Q000706:statistics & numerical data*; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012044:Regression Analysis; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014600:Utilization Review