A new Institute for Clinical Evaluative Sciences (ICES) study shows that increases in the use of coronary angiography (the x-ray image of the heart and blood vessels) for heart attack patients in Ontario began nearly a year before the first available scientific evidence demonstrating its benefit.
“While many view the proliferation of cardiac technology as a direct policy response to emerging scientific evidence, up until now, the extent to which its growth has risen in tandem with scientific clinical trial evidence has remained unclear,” said Dr. David Alter, ICES senior scientist and senior author of the study.
To study this issue further, investigators tracked patients 66 years of age and older admitted to Ontario hospitals for a heart attack between 1992 and 2004. Among these patients, they examined the point of maximum growth for the use of coronary angiography, as well as statin drug therapy use as a non-technology medical comparator. These growth points were compared with the corresponding publication dates of the first positive evidence for the use of angiography and statins in heart attack patients as obtained from published randomized controlled trials.
The results showed that the point of maximum growth for angiography use was in September 1998, 11 months before the publication of the first positive randomized controlled trial demonstrating its benefit. Conversely, the point of maximum growth for statin therapy use was in October 1998, nearly four years after the first positive randomized controlled trial demonstrating its benefits. These findings were consistent regardless of the presence of on-site cardiac catheterization facilities at the admitting institution and patient illness severity levels.
“There are several factors which may explain the lack of alignment between the use of diagnostic technology and evidence of health outcomes,” said Dr. Alter.
“First, regulatory standards for diagnostic technologies are different than for drug technologies. Evidence from well-designed clinical trials are required before a medication goes on the market, but diagnostic technologies are often used prior to such trials.
"Second, human and/or societal attributes may be biased in favour of the early use of new and evolving technologies over established medical therapies. There are also economic and market-driven incentives which may favour earlier or premature use of technologies.”
Dr. Alter stresses that the “poor alignment between technology proliferation and scientific evidence may undermine a system’s resource efficiency by using more costly and less effective technologies, rather than less costly and more effective medical interventions. In addition, the rapid adoption of technology before making adequate health care assessments may challenge the ability to evaluate those technologies in the future because the use of such technologies, however unproven, become thought of as ‘commonplace’ by physicians and their patients.
“Clinical decision leaders must continue to advocate for suitable health technology studies to ensure that patients are receiving treatment that is consistent with and supported by current scientific evidence,” he said.
The study, “Coronary angiography following acute myocardial infarction in Ontario, Canada”, is in the April 23, 2007 issue of the Archives of Internal Medicine.
Author affiliations: ICES (Drs. Austin, Alter, and Ms. Chong); Departments of Medicine (Drs. Singh and Alter), Public Health Sciences (Drs. Austin and Alter), and Health Policy, Management and Evaluation (Drs. Austin and Alter), University of Toronto; The Division of Cardiology and the Li Ka Shing Knowledge Institute of St. Michael’s Hospital (Dr. Alter).
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.
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