title: Influence of projected complication rates on estimated appropriate use rates for carotid endarterectomy. Appropriateness Project Investigators. Academic Medical Center Consortium.
abstract: OBJECTIVE
  To examine specifically the influence of estimated perioperative mortality and stroke rate on the assessment of appropriateness of carotid endarterectomy.
  
  
  METHODS
  An expert panel convened to rate the appropriateness of a variety of potential indications for carotid endarterectomy based on various rates of perioperative complications. We then applied these ratings to the charts of 1,160 randomly selected patients who had carotid endarterectomy in one of the 12 participating academic medical centers.
  
  
  METHODS
  An expert panel evaluated indications for carotid endarterectomy using the modified Delphi approach. Charts of patients who received surgery were abstracted, and clinical indications for the procedure as well as perioperative complications were recorded. To examine the impact of surgical risk assessment on the rates of appropriateness, three different definitions of risk strata for combined perioperative death or stroke were used: Definition A, low risk < 3 percent; Definition B, low risk < 5 percent; and Definition C, low risk < 7 percent.
  
  
  RESULTS
  Overall hospital-specific mortality ranged from 0 percent to 4.0 percent and major complications, defined as death, stroke, intracranial hemorrhage, or myocardial infarction, varied from 2.0 percent to 11.1 percent. Most patients (72 percent) had surgery for transient ischemic attack or stroke; 24 percent of patients were asymptomatic. Most patients (82 percent) had surgery on the side of a high-grade stenosis (70-99 percent). When the thresholds for operative risk were placed at the values defined by the expert panel (Definition A), only 33.5 percent of 1,160 procedures were classified as "appropriate." When the definition of low risk was shifted upward, the proportion of cases categorized as appropriate increased to 58 percent and 81.5 percent for Definitions B and C, respectively.
  
  
  CONCLUSIONS
  Despite the high proportion of procedures performed for symptomatic patients with a high degree of ipsilateral extracranial carotid artery stenosis and generally low rates of surgical complications at the participating institutions, the overall rate of "appropriateness" using a perioperative complication rate of < 3 percent was low. However, the rate of "appropriateness" was extremely sensitive to judgments about a single clinical feature, surgical risk. These data show that before applying such "appropriateness" ratings, it is crucial to perform sensitivity analyses in order to assess the stability of the results. Results that are robust to moderate in variation in surgical risk provide a much sounder basis for policy making than those that are not.
authors.affiliation: Center for Health Policy Research and Education, Duke University, Durham, NC 27708-0253, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Matchar
authors.forename: E Z
authors.initials: EZ
authors.lastname: Oddone
authors.forename: D C
authors.initials: DC
authors.lastname: McCrory
authors.forename: L B
authors.initials: LB
authors.lastname: Goldstein
authors.forename: P B
authors.initials: PB
authors.lastname: Landsman
authors.forename: G
authors.initials: G
authors.lastname: Samsa
authors.forename: R H
authors.initials: RH
authors.lastname: Brook
authors.forename: C
authors.initials: C
authors.lastname: Kamberg
authors.forename: L
authors.initials: L
authors.lastname: Hilborne
authors.forename: L
authors.initials: L
authors.lastname: Leape
authors.forename: R
authors.initials: R
authors.lastname: Horner
mesh_terms: D000046:Academic Medical Centers / Q000706:statistics & numerical data; D000368:Aged; D016893:Carotid Stenosis / Q000601:surgery*; D002561:Cerebrovascular Disorders / Q000209:etiology / Q000601:surgery; D003697:Delphi Technique; D016894:Endarterectomy, Carotid / Q000009:adverse effects* / Q000401:mortality / Q000706:statistics & numerical data; D005260:Female; D006302:Health Services Research; D017052:Hospital Mortality; D006801:Humans; D007431:Intraoperative Complications / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014600:Utilization Review