Background: Recent studies of national practice patterns suggest that there is inconsistency in the appropriateness of referrals for cardiac stress testing. However, little is known about the prevalence of relevant clinical outcomes such as coronary revascularization or acute myocardial infarction (AMI) after stress testing.
Methods: Using administrative claims from a large national private insurer, we conducted an observational cohort study of patients aged 25-64 who underwent de novo stress testing from 2006-2012. We excluded patients with a prior diagnosis of coronary artery disease, heart failure, or stroke. We calculated rates of AMI and coronary angiography with or without revascularization in the year following stress testing. We estimated logistic regression models that included demographic characteristics (age, sex, and race) and relevant comorbidities (diabetes, hypertension, and dyslipidemia). Finally, we stratified the cohort into quintiles based on their risk of having an AMI or revascularization event in order to describe the characteristics of patients at lowest and highest risk.
Results: We identified 564,313 patients (mean age 50, 49% women, 73% white) who underwent stress testing during the study period. Among these patients, 15% had diabetes, 37% had hypertension, and 42% had dyslipidemia. Within one year, 2.5% of the cohort underwent coronary revascularization or were hospitalized for AMI, and 2.7% underwent coronary angiography without revascularization. In the risk-stratified analysis, 0.5% of patients in the lowest risk quintile had an AMI or revascularization event, compared to 6.2% in the highest risk quintile (p<.001). Compared to the highest risk quintile, patients in the lowest risk quintile were younger (mean age 40 versus 58 years; p<.001), more likely to be female (85% versus 0%; p<.001), more likely to be non-white (36% versus 16%; p<.001), and less likely to have comorbidities (Table).
Conclusion: The percentage of commercially insured U.S. patients who had an AMI or revascularization event within 1 year of stress testing was small. In the lowest risk quintile, the a priori prevalence of coronary disease risk factors was low, and the rates of subsequent AMI and revascularization was extremely low, raising questions about the value of stress testing in this subgroup.