Objectives: To compare the types of patients selected for coronary angiography (CA) and coronary artery bypass graft (CABG) surgery, and the appropriateness of the procedures performed on these patients in a random sample of cases in British Columbia and Ontario.
Design: Retrospective randomized medical record review.
Setting: All hospitals performing CA and/or CABG in British Columbia and Ontario in fiscal year 1989/90.
Patients: For CA, 395 randomly selected patients in Ontario and 139 randomly selected patients in British Columbia; for CABG, 431 randomly selected patients in Ontario and 125 randomly selected patients in British Columbia.
Main outcome measures: Case selection was measured in terms of the demographic and clinical characteristics of patients undergoing the procedures. Appropriateness was measured by comparing the clinical characteristics of patients undergoing the procedures with explicit criteria established by a panel of Canadian physicians. The yield from CA was measured as the proportion of patients who were found to have insignificant anatomical disease.
Results: Analysis of patients selected for CA showed that sample patients from Ontario were less likely than those from British Columbia to be female (25% versus 37%, respectively, P = 0.012) and less likely to have undergone a previous revascularization (12% versus 24%, respectively, P = 0.005). The distribution of main indications for CA differed between the two provinces (P = 0.002), with Ontario patients more likely to have chronic stable angina (45% versus 24%) and less likely to have unstable angina (16% versus 26%). For CABG, sample patients from Ontario were less likely to be 65 years of age or older (32% versus 45%, P = 0.016) and more likely to have an ejection fraction less than 35% (14% versus 5%, P = 0.006). The distribution of the main indications for CABG differed (P < 0.001), with Ontario patients more likely to have chronic stable angina (68% versus 38%) and less likely to have unstable angina (20% versus 43%). There was no statistically significant difference in CA cases rated as inappropriate (8.4% in Ontario versus 10.8% in British Columbia, P = 0.396) or CABG cases rated as inappropriate (3.9% in Ontario versus 2.4% in British Columbia, P = 0.393). There were no statistically significant differences in the proportion of CA that yielded insignificant anatomical disease (17.5% in Ontario versus 18.4% in British Columbia, P = 0.355).
Conclusions: There were differences between Ontario and British Columbia in the demographic and clinical characteristics of patients selected for CA and CABG. This may indicate differences in the referral process in the two provinces. Despite these differences the rates of inappropriate procedures and the yield from CA were similar.