Volume and Outcome in Coronary Artery Bypass Graft Surgery: True Association or Artefact?

Overview

Journal BMJ

Specialty General Medicine

Date 1995 Jul 15

PMID 7613425

Citations 26

Authors

A J Sowden

J J Deeks

T A Sheldon

Affiliations

Soon will be listed here.

Abstract

Objectives: To examine the evidence for a relation between volume of coronary artery bypass graft surgery and hospital death rates, and to assess the degree to which this could be due to confounding because of differences in case mix.

Subjects: People receiving coronary artery bypass graft surgery in the United States.

Design: A systematic review of empirical studies examining the relation between volume and outcome of coronary artery bypass graft surgery. Studies were scored according to degree of adjustment for case mix. Above 200 procedures a year was regarded as high volume.

Results: Fifteen studies were identified, all of which used observational data from the United States for 1972-92. Six were included in the analysis, one was included in a sensitivity analysis, and eight were excluded because of duplicate analyses of data sources and methods of reporting results. The seven studies analysed reported a reduced mortality with increased volume. Studies with better adjustment for case mix, however, indicated less reduction in mortality with increased volume (P = 0.04). The apparent advantages of higher volume also decreased over time (P < 0.001).

Conclusions: The evidence for reduced mortality in hospitals with a high volume of coronary artery bypass graft surgery is based entirely on observational studies. These studies may have over-estimated the benefit of increased volume because of poor adjustment for case mix. It signals the need for caution in interpreting the results of observational studies that examine the relation between volume and outcome.

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References

Luft H, Bunker J, Enthoven A . Should operations be regionalized? The empirical relation between surgical volume and mortality. N Engl J Med. 1979; 301(25):1364-9. DOI: 10.1056/NEJM197912203012503. View

Riley G, Lubitz J . Outcomes of surgery among the Medicare aged: surgical volume and mortality. Health Care Financ Rev. 1986; 7(1):37-47. PMC: 4191511. View

Maerki S, Luft H, Hunt S . Selecting categories of patients for regionalization. Implications of the relationship between volume and outcome. Med Care. 1986; 24(2):148-58. DOI: 10.1097/00005650-198602000-00006. View

Sloan F, Perrin J, Valvona J . In-hospital mortality of surgical patients: is there an empiric basis for standard setting?. Surgery. 1986; 99(4):446-54. View

Showstack J, Rosenfeld K, Garnick D, Luft H, SCHAFFARZICK R, Fowles J . Association of volume with outcome of coronary artery bypass graft surgery. Scheduled vs nonscheduled operations. JAMA. 1987; 257(6):785-9. View

Rosenfeld K, Luft H, Garnick D, McPhee S . Changes in patient characteristics and surgical outcomes for coronary artery bypass surgery 1972-82. Am J Public Health. 1987; 77(4):498-500. PMC: 1646937. DOI: 10.2105/ajph.77.4.498. View

Luft H, Hunt S, Maerki S . The volume-outcome relationship: practice-makes-perfect or selective-referral patterns?. Health Serv Res. 1987; 22(2):157-82. PMC: 1065430. View

Hughes R, Hunt S, Luft H . Effects of surgeon volume and hospital volume on quality of care in hospitals. Med Care. 1987; 25(6):489-503. DOI: 10.1097/00005650-198706000-00004. View

Hlatky M, Califf R, Harrell Jr F, Lee K, Mark D, Pryor D . Comparison of predictions based on observational data with the results of randomized controlled clinical trials of coronary artery bypass surgery. J Am Coll Cardiol. 1988; 11(2):237-45. DOI: 10.1016/0735-1097(88)90086-1. View

10.

Hannan E, ODonnell J, Kilburn Jr H, Bernard H, Yazici A . Investigation of the relationship between volume and mortality for surgical procedures performed in New York State hospitals. JAMA. 1989; 262(4):503-10. View

11.

Garnick D, Luft H, McPhee S, Mark D . Surgeon volume vs hospital volume: which matters more?. JAMA. 1989; 262(4):547-8. View

12.

Luft H, Garnick D, Mark D, Peltzman D, Phibbs C, Lichtenberg E . Does quality influence choice of hospital?. JAMA. 1990; 263(21):2899-906. View

13.

DesHarnais S, McMahon Jr L, Wroblewski R, HOGAN A . Measuring hospital performance. The development and validation of risk-adjusted indexes of mortality, readmissions, and complications. Med Care. 1990; 28(12):1127-41. View

14.

Williams S, Nash D, Goldfarb N . Differences in mortality from coronary artery bypass graft surgery at five teaching hospitals. JAMA. 1991; 266(6):810-5. View

15.

Banta D, Bos M . The relation between quantity and quality with coronary artery bypass graft (CABG) surgery. Health Policy. 1991; 18(1):1-10. DOI: 10.1016/0168-8510(91)90139-o. View

16.

Zelen J, Bilfinger T, Anagnostopoulos C . Coronary artery bypass grafting. The relationship of surgical volume, hospital location, and outcome. N Y State J Med. 1991; 91(7):290-2. View

17.

Hannan E, Kilburn Jr H, Bernard H, ODonnell J, Lukacik G, Shields E . Coronary artery bypass surgery: the relationship between inhospital mortality rate and surgical volume after controlling for clinical risk factors. Med Care. 1991; 29(11):1094-107. View

18.

Dickersin K, Min Y, Meinert C . Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards. JAMA. 1992; 267(3):374-8. View

19.

Farley D, Ozminkowski R . Volume-outcome relationships and in-hospital mortality: the effect of changes in volume over time. Med Care. 1992; 30(1):77-94. DOI: 10.1097/00005650-199201000-00009. View

20.

Whitehead A, Whitehead J . A general parametric approach to the meta-analysis of randomized clinical trials. Stat Med. 1991; 10(11):1665-77. DOI: 10.1002/sim.4780101105. View