Wednesday, October 21, 2009

First-in-kind trial examines how diagnostic tests impact patients' later health
by Kelly Shaw

The DCRI's Pamela S. Douglas, MD, will lead a new 10,000 patient trial comparing different cardiac diagnostic tests in real-world settings in order to learn how these tests impact patient outcomes.

Douglas said there is limited information currently available to clinicians about how functional diagnostic tests compare, in terms of accuracy and patient outcomes, to newer imaging tests. This first of its kind trial will provide valuable information to clinicians who need to diagnose chest pain in patients and are uncertain of whether to use a functional test (stress test) or a test which provides images of the coronary arteries, such as coronary computed tomography angiogram ( CTA ).

PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) will enroll patients at 150 sites where symptomatic patients will be randomized to receive either a functional test or to have a cardiac CTA to determine if they have heart disease. They will follow patients for two-four years, looking at the numbers of patients who have heart attacks, strokes, hospitalization for unstable angina, death, or other major complications.

The trial sites will include primary care settings, urgent care sites, and cardiology practices to best reflect the different settings that patients actually seek care for chest pain.

The study is funded by four grants totaling $32 million grant from the National Heart, Lung, and Blood Institute (NHLBI). Other lead investigators are Daniel Mark, MD and Kerry Lee, PhD from DCRI and Udo Hoffmann, MD from MGH.

“We are not just looking at one step but an entire process,” said Douglas. “We will be evaluating not just a test but an approach for diagnosing symptoms and choosing a treatment plan.”

By determining the impact of diagnostic testing on patient health, PROMISE's results will help define care and shape health policy for the millions of people referred for stress testing each year.

Functional tests, such as having a patient walk on a treadmill while hooked up to an ECG, test for the significance of blockages in the arteries leading to the heart by seeing if the blood flow is limited when the heart begins to work harder. Imaging tests instead look for blockages in blood vessels that might indicate heart disease or the potential for heart problems.

Stress tests have been used routinely for years to diagnose heart disease, while CTAs are newer and not as widely available. Reimbursement is also not as clear-cut for CTAs, and Douglas hopes that the PROMISE study will help demonstrate the value of CTAs in terms of patient outcomes.

The local doctors in the trial will be able to decide what course of action, if any, is necessary for a patient after conducting a stress test or using a CTA.

The trial is also unique because previous cardiac imaging studies have generally focused on diagnostic accuracy but not on patient outcomes. Those few that do focus on immediate results such as fewer hours in emergency rooms for patients with chest pain. Since diagnostic tests are one of the fastest growing medical expenses, Douglas says it is important to study the true value of these tests in terms of patient outcomes.

The PROMISE trial is part of the work of the DCRI imaging program, which is focused on imaging quality and outcomes.