Evidence-base and Cost-effectiveness of Cardiothoracic Imaging
In medicine, which retains many traits of an art over being a pure science, the closest thing to proof is evidence on the beneficial effects, or lack thereof, of a given medical measure. Unfortunately, our field of medical imaging has traditionally struggled with the task of creating unequivocal evidence that our tests and techniques work, i.e. make people live longer, healthier, and happier. Previous generations of medical imagers felt far less pressure to prove the effectiveness of their methods and could happily hone and practice their skills as respected diagnosticians within their institutions. Too prevalent and intuitive was the certainty that quality imaging, regardless whether the test results exclude or confirm disease, alleviates doubt in medicine and beneficially steers patient management. Unfortunately, this archetypical confidence in the power of imaging has eroded along with our general ability and willingness to trust.
One fundamental confounder when seeking to build evidence in medical imaging is the fact that the effect of our craft on patient outcomes is difficult to analyze and measure in isolation. Too entwined are imaging results with patient-related factors, compliance, and medical management decisions subsequent to imaging as to allow a clear-cut separation of the role of imaging from the myriad of other vagaries that determine a patient's eventual outcome. In other words, the best possible imaging will not result in improved outcomes if post-imaging management decisions are poor. Secondly, in previous decades the quality of a test was often measured by its prognostic abilities, i.e. the power to differentiate patients who will do fine from those who will suffer adverse outcomes. There are a variety of medical imaging tests that have garnered prominent positions in everyday patient care founded in the overwhelming evidence-base supporting their prognostic power. However, although “prognosis” and “outcome” have often been used synonymously when discussing the quality of a test, they are far from being the same. Moreover, these days, “outcome” is no longer the difference between patients who live or die, but a multifaceted, very granular, and rather fickle notion. One of the more popular concepts to come to grips with the desire to appraise the effectiveness of medical interventions is that of the quality-adjusted life year (QUALY). This unit seeks to gauge the incremental gain in quantity and quality of life attributable to a medical intervention, i.e. the number of years that patients live happy and healthy after said medical measure and the associated cost. Needless to say, this concept has been slow to find entry and application in our world of medical imaging.
However, there is a silver lining. Cardiothoracic disease is clearly one of the biggest cost items in medicine. Although imaging constitutes only a minor portion of the overall expenditure of battling cardiothoracic disease, medical imagers worldwide are heeding the call and are rallying to create the evidence in support of our methods. Subsequently, the much needed evidence base that lives up to the requirements of stringent quality criteria is accumulating much more rapidly and convincingly in cardiothoracic imaging than in any other subspecialty. This special JTI symposium is a wonderful testimony to these vigorous efforts occurring simultaneously worldwide.