Embargoed for Release 1 p.m. PT April 21, 1998
Roxanne Yamaguchi Moster
(310) 206-1960
[email protected]
UCLA STUDY CALLS FOR IMPROVED CT SCAN INTERPRETATION SKILLS BY DOCTORS TO ENSURE SAFE USE OF "CLOT-BUSTING" STROKE DRUGS
A new UCLA study has revealed that many physicians may lack the training necessary to interpret CT scans and safely identify stroke patients who may benefit from "clot-busting" drug therapies.
The accurate interpretation of CT scans in diagnosing the type of stroke suffered by a patient can be a life or death decision.
Blood clots that form in the brain or that drift there from the heart or other sites cause about 85 percent of strokes, called ischemic strokes. Pysicians can treat this condition effectively with thrombolytic drugs, such as tissue plasminogen activator (TPA).
But, for a second type of stroke caused by ruptured vessels, called hemorrhagic stroke, a dose of TPA can prove deadly because it can increase the risk of further bleeding. Since TPA may produce lethal bleeding in patients with the less common hemorrhagic stroke, no patients with evidence of bleeding on CT scans should receive thrombolytic therapy.
The objective of the study by the UCLA Department of Medicine and UCLA Stroke Center, published in the April 22 issue of the Journal of the American Medical Association, was to determine how well emergency physicians, neurologists and general radiologists identified CT scans of the brain showing brain hemorrhage.
TPA, first approved for stroke victims two years ago, works by breaking up clots which plug arteries and restores blood flow to the brain. But in order to be effective, TPA must be administered within three hours of the onset of symptoms, requiring the treating physicians to complete and rapidly interpret a CT scan to make sure the stroke is the ischemic type that can be treated by TPA.
The UCLA study revealed, however, that the sample of physicians studied did not, on
average, have the skills needed to recognize hemorrhage on CT scans and determine which patients may safely receive thrombolytic therapy, such as TPA.
"The potential consequences to the patient and the physician of administering thrombolytic therapy after failing to recognize hemorrhage on the CT scan could be disastrous," said UCLA emergency medicine specialist Dr. David L. Schriger, the study's principal investigator.
"In clinical trials of thrombolytic drugs for stroke, CT scans were read with near perfect sensitivity for hemorrhage," said Schriger. "We would hope this high standard, ideally detecting over 99 percent of hemorrhages, will be maintained when treatment is provided in a non-experimental setting. Our study demonstrates that while some members of each physician group tested were capable of identifying hemorrhage with perfect or near-perfect sensitivity, the majority of those tested were not."
The UCLA study urges physicians involved in the care of patients with acute stroke to ensure that the interpretation of the CT scan reliably identifies intracranial hemorrhage when present. This may be accomplished by providing physicians with additional training in the interpretation of brain CT scans or by obtaining consultation through teleradiology or other systems that facilitate immediate scan interpretation by qualified readers.
The UCLA researchers tested 103 doctors on their ability to correctly interpret five types of CT scans that could potentially portray a stroke patient: (1) normal scans, (2) scans showing hemorrhage, (3) scans showing acute ischemic stroke, (4) scans showing an old stroke and (5) scans showing calcification (the calcium can be mistaken for blood). Each doctor tested was given five typical CT scans to read. Those who interpreted them all correctly were given 10 scans of higher difficulty. Others were given an additional 10 typical scans to review.
Among the doctors tested, 78 percent incorrectly interpreted at least one of the five scans in the initial series, and even the best performers misinterpreted a substantial number of scans. Physicians read 77 percent of all CT scans correctly. Of the CT scans Sixty-seven percent of readings by emergency physicians were correct. Both the neurologists and radiologists correctly interpreted 83 percent of the CT scans they read.
Eighty-two percent of CT scans containing hemorrhagic stroke were read accurately. Fifty-two percent of the radiologists, 40 percent of the neurologists and 17 percent of the emergency physicians interpreted every CT scans demonstrating hemorrhagic stroke they saw correctly.
Stroke is the main cause of adult disability and the third leading cause of death in the U.S. Until recently, there was virtually nothing doctors could do for the 550,000 Americans who have strokes each year, many of whom suffer loss of physical function, cognitive skills,
memory and personality. Stroke and brain injury together cost the nation an estimated $60 billion a year.
Collaborating on the study with Schriger were Drs. Mary Kalafut, Sidney Starkman, Michelle Krueger and Jeffrey Saver, representing the UCLA Emergency Medicine Department, UCLA Stroke Center and UCLA School of Medicine.
-UCLA-
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