title: Surgical candidacy and selection biases in nonemergent left main stenting: implications for observational studies.
abstract: OBJECTIVE
  This study sought to characterize reasons for surgical ineligibility in patients undergoing nonemergent unprotected left main (ULM) percutaneous coronary intervention (PCI) and to assess the potential for these reasons to confound comparative effectiveness studies of coronary revascularization.
  
  
  BACKGROUND
  Although both PCI and coronary artery bypass graft surgery are treatments for ULM disease, some patients are not eligible for both treatments, which may result in treatment selection biases.
  
  
  METHODS
  In 101 consecutive patients undergoing nonemergent ULM PCI, mixed methods were used to determine the prevalence of treatment selection dictated by surgical ineligibility and to identify the reasons cited for avoiding coronary artery bypass graft surgery. We then determined whether these reasons were captured by the ACC-NCDR (American College of Cardiology-National Cardiovascular Data Registry) Cath-PCI dataset to assess the ability of this registry to account for biases in treatment selection. Finally, the association of surgical eligibility with long-term outcomes after ULM PCI was assessed.
  
  
  RESULTS
  Treatment selection was dictated by surgical ineligibility in over half the ULM PCI cohort with the majority having reasons for ineligibility not captured by the ACC-NCDR. Surgical ineligibility was a significant predictor of mortality after adjustment for Society of Thoracic Surgeons (hazard ratio [HR]: 5.4, 95% confidence interval [CI]: 1.2 to 25), EuroSCORE (European System for Cardiac Operative Risk Evaluation) (HR: 5.9, 95% CI: 1.3 to 27), or NCDR mortality scores (HR: 6.2, 95% CI: 1.4 to 27).
  
  
  CONCLUSIONS
  Surgical ineligibility dictating treatment selection is common in patients undergoing nonemergent ULM PCI, occurs on the basis of risk factors not captured by the ACC-NCDR, and is independently associated with worse long-term outcomes after adjusting for standard risk scores.
authors.affiliation: Division of Cardiology, Kaiser Permanente Medical Center, San Francisco, California 94115, USA. edward.j.mcnulty@kp.org
authors.forename: Edward J
authors.initials: EJ
authors.lastname: McNulty
authors.forename: William
authors.initials: W
authors.lastname: Ng
authors.forename: John A
authors.initials: JA
authors.lastname: Spertus
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Zaroff
authors.forename: Robert W
authors.initials: RW
authors.lastname: Yeh
authors.forename: Xiushi M
authors.initials: XM
authors.lastname: Ren
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lundstrom
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000401:mortality; D015982:Bias; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000401:mortality; D003324:Coronary Artery Disease / Q000401:mortality / Q000601:surgery / Q000628:therapy*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D016016:Proportional Hazards Models; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D012495:San Francisco; D016896:Treatment Outcome