When is it right to be wrong?

Validation of the appropriate use criteria for coronary angiography: a cohort study

BACKGROUND

The use of invasive coronary angiography in stable ischemic heart disease (IHD) varies widely.

OBJECTIVE

To validate the 2012 appropriate use criteria for diagnostic catheterization by examining the relationship between the appropriateness of cardiac catheterization in patients with suspected stable IHD and the proportion of patients with obstructive coronary artery disease (CAD) and subsequent revascularization.

DESIGN

Population-based, observational, multicenter cohort study.

SETTING

The Cardiac Care Network, a registry of all patients having elective angiography at 18 hospitals in Ontario, Canada, between 1 October 2008 and 30 September 2011.

PATIENTS

Persons without prior coronary revascularization or myocardial infarction who had angiography for suspected stable CAD.

MEASUREMENTS

Appropriateness scores were ascertained by using data collected at the time of the index angiography and were categorized as appropriate, inappropriate, or uncertain.

RESULTS

Among the final cohort of 48 336 patients, 58.2% of angiographic studies were classified as appropriate, 10.8% were classified as inappropriate, and 31.0% were classified as uncertain. Overall, 45.5% of patients had obstructive CAD. In patients with appropriate indications for angiography, 52.9% had obstructive CAD, with 40.0% undergoing revascularization. In those with inappropriate indications, 30.9% had obstructive CAD and 18.9% underwent revascularization; in those with uncertain indications, 36.7% had obstructive CAD and 25.9% had revascularization. Although more patients with appropriate indications had obstructive CAD and underwent revascularization (P < 0.001), a substantial proportion of those with inappropriate or uncertain indications had important coronary disease.

LIMITATION

Data were not available on whether symptoms were atypical.

CONCLUSION

Despite the association between appropriateness category and obstructive CAD, this study raises concerns about the ability of the appropriate use criteria to guide clinical decision making.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research.

Impact of system and physician factors on the detection of obstructive coronary disease with diagnostic angiography in stable ischemic heart disease

BACKGROUND

Wide variation exists in the detection rate of obstructive coronary artery disease (CAD) with elective coronary angiography for suspected stable ischemic heart disease. We sought to understand the incremental impact of nonclinical factors on this variation.

METHODS AND RESULTS

We included all patients who underwent coronary angiography for possible suspected stable ischemic heart disease, from October 1, 2008, to September 30, 2011, in Ontario, Canada. Nonclinical factors of interest included physician self-referral for angiography, the physician type (invasive or interventional), and hospital type. Hospitals were categorized into diagnostic angiogram only centers, stand-alone percutaneous coronary intervention centers, or full service centers with coronary artery bypass surgery available. Multivariable hierarchical logistic models were developed to identify system and physician-level predictors of obstructive CAD, after adjustment for patient factors. Our cohort consisted of 60 986 patients, of whom 31 726 had obstructive CAD (52.0%), with significant range across hospitals from 37.3% to 69.2%. Fewer self-referral patients (49.8%) had obstructive CAD compared with nonself-referral patients (53.5%), with an odds ratio of 0.89 (95% confidence interval, 0.86-0.93; P<0.001). Angiograms performed by invasive physicians had a lower likelihood of obstructive CAD compared with those by interventional physicians (48.2% versus 56.9%; odds ratio, 0.85; 95% confidence interval, 0.81-0.90; P<0.001). Fewer angiograms at diagnostic only centers showed obstructive CAD (42.0%) compared with full service centers (55.1%; odds ratio, 0.62; 95% confidence interval, 0.39-0.98; P=0.04). Nonclinical factors accounted for 23.8% of the variation between hospitals.

CONCLUSIONS

Physician and system factors are important predictors of obstructive CAD with coronary angiography.