Sex Differences in Access to Coronary Revascularization after Cardiac Catheterization: Importance of Detailed Clinical Data

  1. William A. Ghali, MD, MPH;
  2. Peter D. Faris, PhD;
  3. P. Diane Galbraith, BN;
  4. Colleen M. Norris, MSc;
  5. Michael J. Curtis, MD;
  6. L. Duncan Saunders, PhD;
  7. Vladimir Dzavik, MD;
  8. L. Brent Mitchell, MD;
  9. Merril L. Knudtson, MD; and
  10. for the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Investigators*
  1. From University of Calgary, Calgary; University of Alberta, Edmonton; and the APPROACH Project Offices, Calgary and Edmonton, Alberta, Canada.

    Abstract

    Background: Although some studies suggest that access to cardiac procedures may differ by sex, others have found no evidence of gender bias in cardiac care.

    Objective: To study rates of percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery in men and women after cardiac catheterization.

    Design: Cohort study with prospective data collection.

    Setting: Alberta, Canada.

    Patients: Persons undergoing cardiac catheterization between 1 January 1995 and 31 December 1998 (n = 21 816).

    Measurements: The occurrence of revascularization procedures (PCI or CABG) in the year after cardiac catheterization was measured. Unadjusted revascularization rates, partially adjusted rates (adjusted for clinical variables available in most databases, including administrative databases), and fully adjusted rates (additionally adjusted for extent of coronary artery disease and ejection fraction) were also evaluated.

    Results: The unadjusted relative risk was 0.67 (95% CI, 0.65 to 0.71) for the end point of any revascularization in women relative to men. The relative risk increased to 0.69 (CI, 0.66 to 0.72) with partial adjustment and to 0.98 (CI, 0.94 to 1.03) with full adjustment, indicating equivalent access to revascularization for men and women. For PCI, the corresponding relative risks were 0.77 (CI, 0.73 to 0.82), 0.84 (CI, 0.80 to 0.89), and 1.02 (CI, 0.96 to 1.08). For CABG surgery, the relative risks were 0.54 (CI, 0.51 to 0.58), 0.51 (CI, 0.48 to 0.55), and 0.93 (CI, 0.87 to 1.01).

    Conclusions: In Alberta, Canada, clinical variables fully explain sex differences in rates of revascularization after cardiac catheterization, and misleading conclusions would arise without full adjustment for clinical differences between men and women. Extreme caution is needed in interpreting reports on access to care that use sparsely detailed clinical data sources.

    *For members of the APPROACH Steering Committee, see Appendix.

    Article and Author Information

    • Acknowledgment: The authors thank the Calgary Regional Health Authority and the Capital Health Authority for assistance with on-line data entry by cardiac catheterization laboratory personnel.

    • Grant Support: The APPROACH initiative was initially funded in 1995 by a grant from the Weston Foundation. The ongoing operation of the project has been made possible by contributions from the Province-Wide Services Committee of Alberta Health and Wellness, Merck Frosst Canada, Inc.; Monsanto Canada, Inc.–Searle; Eli Lilly Canada, Inc.; Guidant Corp.; Boston Scientific, Ltd.; Hoffmann–La Roche, Ltd.; and Johnson & Johnson, Inc.–Cordis. Analysis was supported by an operating grant from the Heart and Stroke Foundation of Canada. Dr. Ghali is supported by a Population Health Investigator Award from the Alberta Heritage Foundation for Medical Research, Edmonton, Alberta, and by a Government of Canada Research Chair in Health Services Research.

    • Requests for Single Reprints: William A. Ghali, MD, MPH, Faculty of Medicine, University of Calgary, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada; e-mail, wghali{at}ucalgary.ca.

    • Potential Financial Conflicts of Interest: None disclosed.

    • Current Author Addresses: Dr. Ghali: University of Calgary, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada.

    • Dr. Faris and Ms. Galbraith: c/o Centre for Health and Policy Studies, 3330 Hospital Drive Northwest, Calgary, Alberta T2N 4N1, Canada.

    • Ms. Norris: APPROACH Project Office, 8111 1st Floor ABC, 8440—112 Street, Edmonton, Alberta T6G 2B7, Canada.

    • Drs. Curtis, Mitchell, and Knudtson: Foothills Hospital, 1403—29th Street Northwest, Calgary, Alberta T2N 2T9, Canada.

    • Dr. Saunders: University of Alberta, Room 13-106, 8440—112th Street, Edmonton, Alberta T6G 2B7, Canada.

    • Dr. Dzavik: 200 Elizabeth Street, EN 12-244a, Toronto, Ontario M5G 2C4, Canada.

    • Author Contributions: Conception and design: WA Ghali, LD Saunders, LB Mitchell, ML Knudtson.

    • Analysis and interpretation of the data: WA Ghali, PD Faris, PD Galbraith, CM Norris, MJ Curtis, ML Knudtson.

    • Drafting of the article: WA Ghali.

    • Critical revision of the article for important intellectual content: PD Faris, PD Galbraith, CM Norris, MJ Curtis, LD Saunders, V Dzavik, ML Knudtson.

    • Final approval of the article: WA Ghali, PD Galbraith, MJ Curtis, LD Saunders, V Dzavik, LB Mitchell, ML Knudtson.

    • Provision of study materials or patients: WA Ghali, V Dzavik, ML Knudtson.

    • Statistical expertise: WA Ghali, PD Faris, CM Norris.

    • Obtaining of funding: WA Ghali, LD Saunders, ML Knudtson.

    • Administrative, technical, or logistic support: WA Ghali, PD Galbraith, V Dzavik.

    • Collection and assembly of data: WA Ghali, PD Galbraith, V Dzavik.

    Summary for Patients

    • Summaries for Patients:Clinical Factors Explain Differences in Frequency of Cardiac Procedures between Men and Women after Cardiac Catheterization Ann Intern Med May 21, 2002 136:I40
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    1. Ann Intern Med May 21, 2002 vol. 136 no. 10 723-732
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