The urban public hospital where I completed most of my training as a medical student had a single CT scanner. To ensure that this precious resource was put to effective use, any physician ordering a non-emergent CT scan was required to personally present the patient's case to the on-call Radiology fellow and explain how the result of the scan would potentially change management. Since my attending surgeons were usually too busy to trudge down to the Radiology suite, they deputized their residents to do so, and most of the time my residents passed this thankless task down to the students. Thus, my classmates and I learned early on the difference between appropriate and inappropriate reasons for ordering CT scans.
Today, the widespread availability of CT scanners has made this sort of explicit rationing uncommon in the U.S. In fact, an editorial published last year in AFP reviewed the accumulating evidence that CT scans are highly overused in current medical practice, which puts patients at unnecessary risk of radiation-induced cancers and detection of incidental findings that can lead to overdiagnosis and overtreatment. Identifying overuse of CT scans often isn't easy, though. And some might argue that increasing use of CT scans may have the positive effect of improving diagnosis of common symptoms, allowing physicians to institute appropriate management of serious conditions more quickly.
Family physicians Andrew Coco and David O'Gurek investigated this possibility in a research study published recently in the Journal of the American Board of Family Medicine. They analyzed data on common chest symptom-related emergency department visits from the National Hospital Ambulatory Medical Care Survey from 1997 to 1999 and 2005 to 2007. Unsurprisingly, the proportion of these visits in which a CT scan was performed rose from 2.1% to 11.5% during this time period. However, the proportion of visits that resulted in a clinically significant diagnosis (pulmonary embolism, acute coronary syndrome or MI, heart failure, pneumonia, pleural effusion) actually fell slightly, challenging that notion that increased CT utilization leads to improved detection and treatment of serious health conditions.
In their AFP editorial, Drs. Diana Miglioretti and Rebecca Smith-Bindman recommend that physicians and referring clinicians take several steps to reduce harms from CT scan overuse:
1. Use CT only when it is likely to enhance patient health or change clinical care.
2. When CT is necessary, apply the ALARA (as low as reasonably achievable) principle to radiation doses.
3. Inform patients of CT risks before imaging.
4. Monitor individual exposure over time and provide the information to patients.
Since 2007, AFP has published a series of articles in collaboration with the American College of Radiology on appropriate criteria for diagnostic imaging (including CT) in specific clinical situations. The ACR Appropriateness Criteria are periodically updated, and current versions are available on the ACR website.