Clinical Research
Surgical Candidacy and Selection Biases in Nonemergent Left Main Stenting: Implications for Observational Studies

https://doi.org/10.1016/j.jcin.2011.06.010Get rights and content
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Objectives

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.

Key Words

bias
bypass
comparative effectiveness
risk factors
stents

Abbreviations and Acronyms

CABG
coronary artery bypass graft
CI
confidence interval
HR
hazard ratio
KPNC
Kaiser Permanente Northern California
PCI
percutaneous coronary intervention
ULM
unprotected left main

Cited by (0)

This study was supported by grants from the Community Benefits Grant, Kaiser Foundation Research Institute (to Dr. Lundstrom) and Graduate Medical Education Program, Northern California Kaiser Permanente (to Dr. Ng). Drs. McNulty, Ng, Ren, and Lundstrom are employees of The Permanente Medical Group, Inc. Dr. McNulty receives grant support from the National Institutes of Health. Dr. Spertus has a research contract with American College of Cardiology Foundation; has received grants from American Heart Association, Amgen, Johnson & Johnson, and National Institutes of Health; has received grant support from Atherotech and Roche Diagnostics; and is a consultant for Novartis, United Healthcare, and St. Jude Medical. Drs. Zaroff and Lundstrom receive grant support from the Kaiser Foundation Research Institute. Dr. Yeh is a consultant for the Kaiser Permanente Division of Research and the Harvard Clinical Research Institute. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.