Tuesday, August 21, 2007

The Challenges of Measuring Outcomes with Guidelines

In Circulation’s published-before-print edition this week, results of the CRUSADE trial (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines) were published.

This trial compared the care received by patientswas with acute coronary syndromes (unstable angina, non-Q wave myocardial infarctions) admitted to a specialty cardiology service versus a general medical service. Patient characteristics, the use of American College of Cardiology/American Heart Association guidelines class I recommendations, and in-hospital outcomes by the specialty of the primary in-patient service (cardiology versus noncardiology) in patients from 301 tertiary care hospitals were compared. A total of 35 374 patients (63.2%) were primarily cared for by a cardiology service, and these patients had lower-risk clinical characteristics, but they more commonly received acute (<24 hours) medications, invasive cardiac procedures, and discharge medications and lifestyle interventions.

Their findings? While non–ST-segment elevation acute coronary syndrome patients primarily cared for by a cardiology inpatient service more commonly received evidence-based treatments and had a lower risk of mortality, these patients had lower-risk clinical characteristics (healthier patients did better).

This, then, leads to the question, were the improved outcomes an effect of application of guideline-based therapies, or just selection bias (healthier patients were referred to cardiology because they had fewer co-morbidities)? It was impossible to tell by the data collected.

So why is this study important?

Because performance measures (as determined by application of Class I guideline recommendations for the management of acute coronary syndromes), while measurable, were still unable to determine if improved outcomes were from the application of guideline recommendations, or just a matter of the healthier population to whom these guidelines could be applied.

This throws in to doubt the legitimacy of CMS’s pay for performance initiatives using the application of lock-step guidelines to measure outcomes, since these guidelines are applied disproportionately to healthier patients.


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