Wednesday, January 18, 2012

Curbing overuse of CT scans - and other interventions

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 American Family Physician 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 editorial, Drs. Diana Miglioretti and Rebecca Smith-Bindman recommended 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.

These general points can and should be applied to many other medical interventions, including screening tests and treatments. To paraphrase: Never do anything to a  patient unless you think it may help. When an intervention is necessary, intervene as little as possible. Always inform patients of the risks of any intervention, and monitor their exposure to its harmful effects over time so that they can choose to opt out later, if desired.

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A slightly different version of the above post was first published on the AFP Community Blog.

2 comments:

  1. One of our distinguished surgeons has recommended, based on the study that shows that one can screen for lung cancer with CT scans, that we need to do it. Worse than absurd. Yes, it is better than a plain chest x-ray, but has about 200x the radiation exposure. Such screening has a chance of causing more cancers than it finds..
    This is a good example of syllogism: there is (fair, not great) data to show that mammography screening for breast cancer saves lives, so let's screen for other cancers. And, of course, we don't know what causes breast cancer, unlike lung cancer which is overwhelmingly caused by smoking, so screening makes more sense.

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  2. "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."

    But it does suggest that some patients were not treated for things they didn't have, which can be an important benefit if the treatment has significant risk or cost.

    Peter Elias, MD

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