Shop for Quality or Volume? Volume, Quality, and Outcomes of Coronary Artery Bypass Surgery

  1. Andrew D. Auerbach, MD, MPH;
  2. Joan F. Hilton, ScD;
  3. Judith Maselli, MSPH;
  4. Penelope S. Pekow, PhD;
  5. Michael B. Rothberg, MD, MPH; and
  6. Peter K. Lindenauer, MD, MSc
  1. From the University of California, San Francisco, San Francisco, California, and Baystate Medical Center, Tufts University School of Medicine, Springfield, Massachusetts.

    Abstract

    Background: Care from high-volume centers or surgeons has been associated with lower mortality rates in coronary artery bypass surgery, but how volume and quality of care relate to each other is not well understood.

    Objective: To determine how volume and differences in quality of care influence outcomes after coronary artery bypass surgery.

    Design: Observational cohort.

    Setting: 164 hospitals in the United States.

    Patients: 81 289 patients 18 years or older who had coronary artery bypass grafting from 1 October 2003 to 1 September 2005.

    Measurements: Hospital and surgeon case volumes were estimated by using a data set. Quality measures were defined by whether patients received specific medications and by counting the number of measures missed. Hierarchical models were used to estimate effects of volume and quality on death and readmission up to 30 days.

    Results: After adjustment for clinical factors, lowest surgeon volume and highest hospital volume were associated with higher mortality rates and lower readmission risk, respectively. Patients who did not receive aspirin (odds ratio, 1.89 [95% CI, 1.65 to 2.16) or β-blockers (odds ratio, 1.29 [CI, 1.12 to 1.49]) had higher odds for death, after adjustment for clinical risk factors and case volume. Adjustment for individual quality measures did not alter associations between volume and readmission or death. However, if no quality measures were missed, mortality rates at the lowest-volume centers (adjusted mortality rate, 1.05% [CI, 0.81% to 1.29%]) and highest-volume centers (adjusted mortality rate, 0.98% [CI, 0.72% to 1.25%]) were similar.

    Limitation: Because administrative data were used, the quality measures may not replicate measures collected through chart abstraction.

    Conclusion: Maximizing adherence to quality measures is associated with improved mortality rates, independent of hospital or surgeon volume.

    Primary Funding Source: California HealthCare Foundation.

    Article and Author Information

    • Acknowledgment: The authors acknowledge Erin Hartman, MS, for her expert editorial assistance, as well as Denise Remus, MD, and Kathy Belk for their work in assembling the data set used for this analysis.

    • Grant Support: By the California HealthCare Foundation (grant number 05-1755) and Agency for Healthcare Research and Quality (Patient Safety Research and Training Grant K08 HS11416-02; Dr. Auerbach).

    • Potential Financial Conflicts of Interest: None disclosed.

    • Requests for Single Reprints: Andrew D. Auerbach, MD, MPH, Department of Medicine, Division of Hospital Medicine, University of California, San Francisco, 505 Parnassus Avenue, Box 0131, San Francisco, CA 94143-0131; e-mail, ada{at}medicine.ucsf.edu.

    • Current Author Addresses: Dr. Auerbach and Ms. Maselli: Department of Medicine, Division of Hospital Medicine, University of California, San Francisco, 505 Parnassus Avenue, Box 0131, San Francisco, CA 94143-0131.

    • Dr. Hilton: Department of Epidemiology and Biostatistics, University of California, San Francisco, 505 Parnassus Avenue, San Francisco, CA 94143.

    • Drs. Pekow, Rothberg, and Lindenauer: Baystate Medical Center, Center for Quality and Safety Research, 759 Chestnut Street, Springfield, MA 01199.

    • Author Contributions: Conception and design: A.D. Auerbach, J.F. Hilton, J. Maselli, P.S. Pekow, P.K. Lindenauer.

    • Analysis and interpretation of the data: A.D. Auerbach, J.F. Hilton, J. Maselli, P.S. Pekow, M.B. Rothberg, P.K. Lindenauer.

    • Drafting of the article: A.D. Auerbach, J.F. Hilton, P.S. Pekow, M.B. Rothberg.

    • Critical revision of the article for important intellectual content: A.D. Auerbach, J.F. Hilton, P.S. Pekow, M.B. Rothberg, P.K. Lindenauer.

    • Final approval of the article: A.D. Auerbach, J.F. Hilton, P.S. Pekow, M.B. Rothberg, P.K. Lindenauer.

    • Provision of study materials or patients: A.D. Auerbach, J.F. Hilton, P.S. Pekow, P.K. Lindenauer.

    • Statistical expertise: A.D. Auerbach, J.F. Hilton, P.S. Pekow.

    • Obtaining of funding: A.D. Auerbach, J.F. Hilton, P.S. Pekow.

    • Administrative, technical, or logistic support: A.D. Auerbach, J.F. Hilton, P.S. Pekow.

    • Collection and assembly of data: A.D. Auerbach, J.F. Hilton, P.S. Pekow.

    Comments on This Article

    • The Authors Respond
      • Andrew D Auerbach and
      • Michael Rothberg MD MPH, Peter Lindenauer MD MSc
      Ann Intern Med published online July 15, 2009
    • Shopping for Data: Quality or Volume?
      • Kevin W. Lobdell and
      • Sotiris Stamou, Eric Skipper, Mark Reames, R. Mark Stiegel, Jeko Madjarov, Sara Camp, and Francis Robicsek
      Ann Intern Med published online May 26, 2009
    | Table of Contents

    This Article

    1. Ann Intern Med May 19, 2009 vol. 150 no. 10 696-704
    1. » AbstractFREE
    2. Figures
    3. Full Text
    4. Full Text (PDF)

    Share

    Current Issue

    1. February 7, 2012, 156 (3)
    1. Alert me to current issues
    Most Read Most Read
    Most Commented Most Commented On
    Annals in the News Annals in the News
    Clinical Trials Clinical Trials
    Comparative Effectiveness Comparative Effectiveness
    Hospital Medicine Hospital Medicine
    • Advertisement
    • Advertisement