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CMAJ : Canadian Medical Association Journal logoLink to CMAJ : Canadian Medical Association Journal
. 1998 Jul 1;159(1):25–31.

Coronary artery bypass grafting in Canada: national and provincial mortality trends, 1992-1995

W A Ghali 1, H Quan 1, R Brant 1
PMCID: PMC1229477  PMID: 9679483

Abstract

BACKGROUND: Despite a body of research on outcomes of coronary artery bypass grafting (CABG) in Canada, little is known about Canada-wide outcome trends and interregional differences in outcome. The objectives of this study were to examine Canadian trends in rates of in-hospital death after CABG and to compare provincial risk-adjusted death rates. METHODS: Hospital discharge data were obtained from the Canadian Institute for Health Information and were used to identify complete cohorts of patients who underwent CABG in 8 provinces in fiscal years 1992/93 through 1995/96. Data from Quebec hospitals were not available. A logistic regression model was used to calculate risk-adjusted death rates by year, province, and province and year. RESULTS: A total of 50,357 CABG cases were studied, with an overall death rate of 3.6%. A national trend of decreasing mortality was found, with a risk-adjusted death rate of 3.8% in 1992/93 versus 3.2% in 1995/96 (relative decrease of 17%) (p < 0.001 for difference across years). Some provinces (e.g., Alberta, Manitoba and Ontario) achieved overall declines in death rates over the study period, whereas others (e.g., British Columbia and Saskatchewan) did not. The average severity of illness of patients who underwent CABG differed considerably across provinces. Despite risk adjustment for these differences, provincial death rates varied significantly (p < 0.001). INTERPRETATION: Rates of death after CABG in Canada decreased significantly in a relatively short period. Despite this encouraging finding, there were interprovincial differences in severity of illness and risk-adjusted death rates. This finding raises the possibility of unequal access to CABG and variable quality of care for patients undergoing the surgery across Canadian provinces.

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Selected References

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  1. Anderson G. M., Grumbach K., Luft H. S., Roos L. L., Mustard C., Brook R. Use of coronary artery bypass surgery in the United States and Canada. Influence of age and income. JAMA. 1993 Apr 7;269(13):1661–1666. [PubMed] [Google Scholar]
  2. Cairns J. A., Fuster V., Kennedy J. W. Coronary thrombolysis. Chest. 1992 Oct;102(4 Suppl):482S–507S. doi: 10.1378/chest.102.4_supplement.482s. [DOI] [PubMed] [Google Scholar]
  3. Charlson M. E., Pompei P., Ales K. L., MacKenzie C. R. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373–383. doi: 10.1016/0021-9681(87)90171-8. [DOI] [PubMed] [Google Scholar]
  4. Deyo R. A., Cherkin D. C., Ciol M. A. Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases. J Clin Epidemiol. 1992 Jun;45(6):613–619. doi: 10.1016/0895-4356(92)90133-8. [DOI] [PubMed] [Google Scholar]
  5. Ghali W. A., Ash A. S., Hall R. E., Moskowitz M. A. Statewide quality improvement initiatives and mortality after cardiac surgery. JAMA. 1997 Feb 5;277(5):379–382. [PubMed] [Google Scholar]
  6. Ghali W. A., Hall R. E., Rosen A. K., Ash A. S., Moskowitz M. A. Searching for an improved clinical comorbidity index for use with ICD-9-CM administrative data. J Clin Epidemiol. 1996 Mar;49(3):273–278. doi: 10.1016/0895-4356(95)00564-1. [DOI] [PubMed] [Google Scholar]
  7. Green J., Wintfeld N. Report cards on cardiac surgeons. Assessing New York State's approach. N Engl J Med. 1995 May 4;332(18):1229–1232. doi: 10.1056/NEJM199505043321812. [DOI] [PubMed] [Google Scholar]
  8. Grover F. L., Hammermeister K. E., Burchfiel C. Initial report of the Veterans Administration Preoperative Risk Assessment Study for Cardiac Surgery. Ann Thorac Surg. 1990 Jul;50(1):12–28. doi: 10.1016/0003-4975(90)90073-f. [DOI] [PubMed] [Google Scholar]
  9. Hannan E. L., Kilburn H., Jr, Lindsey M. L., Lewis R. Clinical versus administrative data bases for CABG surgery. Does it matter? Med Care. 1992 Oct;30(10):892–907. doi: 10.1097/00005650-199210000-00002. [DOI] [PubMed] [Google Scholar]
  10. Hannan E. L., Kilburn H., Jr, O'Donnell J. F., Lukacik G., Shields E. P. Adult open heart surgery in New York State. An analysis of risk factors and hospital mortality rates. JAMA. 1990 Dec 5;264(21):2768–2774. [PubMed] [Google Scholar]
  11. Hannan E. L., Kilburn H., Jr, Racz M., Shields E., Chassin M. R. Improving the outcomes of coronary artery bypass surgery in New York State. JAMA. 1994 Mar 9;271(10):761–766. [PubMed] [Google Scholar]
  12. Hartz A. J., Kuhn E. M. Comparing hospitals that perform coronary artery bypass surgery: the effect of outcome measures and data sources. Am J Public Health. 1994 Oct;84(10):1609–1614. doi: 10.2105/ajph.84.10.1609. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Jaglal S. B., Tu J. V., Naylor C. D. Higher in-hospital mortality in female patients following coronary artery bypass surgery: a population-based study. Provincial Adult Cardiac Care Network of Ontario. Clin Invest Med. 1995 Apr;18(2):99–107. [PubMed] [Google Scholar]
  14. Jama J. W., Launer L. J., Witteman J. C., den Breeijen J. H., Breteler M. M., Grobbee D. E., Hofman A. Dietary antioxidants and cognitive function in a population-based sample of older persons. The Rotterdam Study. Am J Epidemiol. 1996 Aug 1;144(3):275–280. doi: 10.1093/oxfordjournals.aje.a008922. [DOI] [PubMed] [Google Scholar]
  15. Jencks S. F. Can large-scale interventions improve care? JAMA. 1997 Feb 5;277(5):419–420. [PubMed] [Google Scholar]
  16. Kirklin J. W., Naftel C. D., Blackstone E. H., Pohost G. M. Summary of a consensus concerning death and ischemic events after coronary artery bypass grafting. Circulation. 1989 Jun;79(6 Pt 2):I81–I91. [PubMed] [Google Scholar]
  17. Landon B., Iezzoni L. I., Ash A. S., Shwartz M., Daley J., Hughes J. S., Mackiernan Y. D. Judging hospitals by severity-adjusted mortality rates: the case of CABG surgery. Inquiry. 1996 Summer;33(2):155–166. [PubMed] [Google Scholar]
  18. O'Connor G. T., Plume S. K., Olmstead E. M., Coffin L. H., Morton J. R., Maloney C. T., Nowicki E. R., Tryzelaar J. F., Hernandez F., Adrian L. A regional prospective study of in-hospital mortality associated with coronary artery bypass grafting. The Northern New England Cardiovascular Disease Study Group. JAMA. 1991 Aug 14;266(6):803–809. [PubMed] [Google Scholar]
  19. O'Connor G. T., Plume S. K., Olmstead E. M., Morton J. R., Maloney C. T., Nugent W. C., Hernandez F., Jr, Clough R., Leavitt B. J., Coffin L. H. A regional intervention to improve the hospital mortality associated with coronary artery bypass graft surgery. The Northern New England Cardiovascular Disease Study Group. JAMA. 1996 Mar 20;275(11):841–846. [PubMed] [Google Scholar]
  20. Parsonnet V., Dean D., Bernstein A. D. A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease. Circulation. 1989 Jun;79(6 Pt 2):I3–12. [PubMed] [Google Scholar]
  21. Peters S., Chagani K., Paddon P., Nair C. Coronary artery bypass surgery in Canada. Health Rep. 1990;2(1):9–26. [PubMed] [Google Scholar]
  22. Peterson E. D., Jollis J. G., Bebchuk J. D., DeLong E. R., Muhlbaier L. H., Mark D. B., Pryor D. B. Changes in mortality after myocardial revascularization in the elderly. The national Medicare experience. Ann Intern Med. 1994 Dec 15;121(12):919–927. doi: 10.7326/0003-4819-121-12-199412150-00003. [DOI] [PubMed] [Google Scholar]
  23. Pine M., Norusis M., Jones B., Rosenthal G. E. Predictions of hospital mortality rates: a comparison of data sources. Ann Intern Med. 1997 Mar 1;126(5):347–354. doi: 10.7326/0003-4819-126-5-199703010-00002. [DOI] [PubMed] [Google Scholar]
  24. Romano P. S., Roos L. L., Luft H. S., Jollis J. G., Doliszny K. A comparison of administrative versus clinical data: coronary artery bypass surgery as an example. Ischemic Heart Disease Patient Outcomes Research Team. J Clin Epidemiol. 1994 Mar;47(3):249–260. doi: 10.1016/0895-4356(94)90006-x. [DOI] [PubMed] [Google Scholar]
  25. Roos L. L., Sharp S. M. Innovation, centralization, and growth. Coronary artery bypass graft surgery in Manitoba. Med Care. 1989 May;27(5):441–452. [PubMed] [Google Scholar]
  26. Silber J. H., Rosenbaum P. R., Schwartz J. S., Ross R. N., Williams S. V. Evaluation of the complication rate as a measure of quality of care in coronary artery bypass graft surgery. JAMA. 1995 Jul 26;274(4):317–323. [PubMed] [Google Scholar]
  27. Théroux P., Ouimet H., McCans J., Latour J. G., Joly P., Lévy G., Pelletier E., Juneau M., Stasiak J., deGuise P. Aspirin, heparin, or both to treat acute unstable angina. N Engl J Med. 1988 Oct 27;319(17):1105–1111. doi: 10.1056/NEJM198810273191701. [DOI] [PubMed] [Google Scholar]
  28. Tu J. V., Mazer C. D., Levinton C., Armstrong P. W., Naylor C. D. A predictive index for length of stay in the intensive care unit following cardiac surgery. CMAJ. 1994 Jul 15;151(2):177–185. [PMC free article] [PubMed] [Google Scholar]
  29. Tu J. V., Naylor C. D. Coronary artery bypass mortality rates in Ontario. A Canadian approach to quality assurance in cardiac surgery. Steering Committee of the Provincial Adult Cardiac Care Network of Ontario. Circulation. 1996 Nov 15;94(10):2429–2433. doi: 10.1161/01.cir.94.10.2429. [DOI] [PubMed] [Google Scholar]
  30. Tu J. V., Pashos C. L., Naylor C. D., Chen E., Normand S. L., Newhouse J. P., McNeil B. J. Use of cardiac procedures and outcomes in elderly patients with myocardial infarction in the United States and Canada. N Engl J Med. 1997 May 22;336(21):1500–1505. doi: 10.1056/NEJM199705223362106. [DOI] [PubMed] [Google Scholar]

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