When technology adoption leads rather than lags guidelines: Imaging diagnosis of pulmonary embolism

Research objective:

Pulmonary embolism (PE) is a common, life-threatening emergency. When the diagnosis of acute PE is confirmed and PE is treated promptly, mortality and chances of recurrence are low. Results from a large multi-center trial (PIOPED II ‘06) found CT angiography of the chest to be an excellent tool for diagnosis of PE, superior to previously-popular ventilation-perfusion (V/Q) scans.

Our objective is to identify whether clinical practice among Medicare patients favors CT over V/Q, despite the common reality that practice badly lags evidence, and to explore whether there are variations based on patient or physician characteristics.

Data and Methods

Using the 2005 Medicare 5% Research Identifiable Files (RIF) claims data, we identify

the tests most commonly used to diagnose or rule out PE, or rule out alternative diagnoses for similar symptoms.

For patients with a diagnosis of PE or PE-related symptoms, and patients identified with PE on an inpatient stay/admission, we calculate the distribution of tests used overall and as a first line of investigation, by place of service and by physician specialty. Logistic regression analyses are used to measure the effect of patient and physician characteristics. on receipt of the five most common diagnostic tests for PE.

Principal findings

Just over 2% of patients who might potentially be suspected of having PE are actually found to have PE.

For patients for whom PE may be suspected , the most common tests were CT or CTA of the chest, echocardiograms, perfusion only scans, and duplex Doppler scans. The vast majority of patients had a chest X-ray.

For approximately a third of the patients with PE, there is no evidence that they had any of the tests recommended for diagnosis of PE.

For patients with symptoms that may be related to PE, the tests used varied depending upon the treating physician's specialty, the site of service, and urban versus rural location, but not upon the patient's characteristics.

Conclusions

Physicians appear to be adopting findings from the literature in their practice even before they were formally released. Even before the release of findings from PIOPED II, CT was in extensive use and V/Q was used relatively little.