Trends in the utilization of noninvasive cardiac diagnostic tests in Ontario from fiscal year 1989/90 to 1992/93

Objective: To describe patterns of utilization of noninvasive cardiac diagnostic tests in Ontario. DESIGN: Retrospective analysis using Ontario Health insurance Plan (OHIP) administrative data. Setting: Ambulatory care settings in Ontario. Main Outcome Measures: First, the volume if service and expenditures on electrocardiograms (ECG), ambulatory ECG, radionuclide angiograms (RNA), echocardiograms, exercise stress tests (EST) and myocardial perfusion scintigrams from 1989/90 to 1992/93; second, the number and speciality of physicians performing these tests. Main Results: Ontario spent $119 million on noninvasive diagnostic cardiology tests in 1992/93, representing 2.67% of total OHIP expenditures. Expenditures on these procedures grew by 49.3% over the four-year period, exceeding the overall OHIP growth rate, and was most rapid for nuclear cardiology and echocardiology. Changing demographics accounted for only minor portion of expenditure growth. Second, age-adjusted utilization rates for EST, myocardial perfusion scintigraphy and RNA were higher for men, but sex differences tended to diminish over time. Third, utilization rates differed markedly by geographic region, and variations were greatest for nuclear medicines studies. Geographic variations tended to attenuated over time. There was also wide variations in the frequency with which physicians performed Doppler studies with two-dimensional echocardiography. Conclusions: The use of noninvasive cardiac diagnosis tests has grown rapidly in recent years. This growth may have been influenced by practice guidelines, by greater diffusion of, and access to, newer technology and by more testing in women. Wide regional variations suggest that clearer practice guidelines are needed concerning the appropriate use of noninvasive cardiac diagnostic investigations.