Mar 02nd 2017

Test Time? Not So Fast...

First, do no harm. (Hippocratic Oath, 100 BC)

That's the vow that doctors make when embarking upon their careers. All clinicians would agree that they want to reduce the likelihood of their patients being unnecessarily exposed to potentially harmful substances. Increasingly today, however, they may be inadvertently exposing their patients to unnecessary potential risks by ordering certain kinds of tests, or ordering these tests too often. Sound decisions about ordering a particular type of test require understanding of the accompanying potential risk versus any potential benefit for the patient. A clinician must consider which option is best for each patient's clinical circumstances, and one of the most useful tools for making that judgment call is a relevant set of evidence- based guidelines.

During a recent presentation at the Tennessee chapter of the American College of Physicians' Scientific Meeting, eviCore assistant medical director Dr. Robert Neaderthal spoke about the importance of using evidence-based guidelines to help weigh the risk-benefit ratios of various types of imaging tests. Consider the use of Computed Tomography (CT), for which the technology has significantly evolved over the past 40 years. Modern CT scans require less time, and the resulting images are highly detailed and far more accurate than those of the older CT technology.

However, this use has posed both potential benefits and risks. According to the U.S. Food and Drug Administration (FDA), the main risks connected with the use of CT scans are "those associated with test results that demonstrate a benign or incidental finding, leading to unneeded, possibly invasive, follow-up tests that may present additional risks and the increased possibility of cancer induction from x-ray radiation exposure." The "effective dose" is used to compare the risk estimates associated with radiation exposure. These effective dose estimates may vary based on the type of procedure, patient size, equipment, and techniques. Using average effective doses, it has been estimated that a chest CT scan may have an effective dose equivalent to that of 350 frontal-view chest x-rays. Furthermore, if the clinician decides to order a CT without contrast and another with contrast, the radiation dose may be doubled. Clinicians must analyze each patient's situation and ask: Is an imaging procedure necessary at this time? If so, which procedure will best meet the patient's diagnostic needs while avoiding any unnecessary exposure to potentially harmful substances such as radiation and contrast material? Evidence- based guidelines such as eviCore's Cardiac Imaging Guidelines and Chest Imaging Guidelines can provide valuable insight based on sound scientific data, and that insight can help clinicians be more confident in their decision-making.

Another example that Dr. Neaderthal highlighted is the nuclear stress test, which is often used to evaluate patients with chest pain or other symptoms that may be caused by coronary artery disease (CAD). Though nuclear stress tests using thallium or sestamibi radioactive tracers are commonly performed, there are several other options available, such as a treadmill exercise test, stress echocardiogram, or stress cardiac MR. These other options have been shown to be equally effective in the evaluation of these cardiac symptoms, depending on the clinical presentation of the patient. And, these other options do not involve the risk of radiation exposure.

Importantly, the decision of which test to perform should be based on the individual patient, the clinical presentation, and an assessment of the patient's risk for CAD. For example, in young patients or those with a low predicitive likelihood of having coronary artery disease, a simple treadmill test that is negative (normal), makes the odds of coronary artery disease extremely low.

Clinicians should consider all the information that is available to them, including their patient's medical history, physical findings, the likelihood of a given disease entity causing the presenting issue, as well as the current professional guidelines. The physician will need to then decide if there is solid scientific support for ordering an imaging test and, if so, consider using a lower risk alternative.

Whether a clinician is considering an imaging test for screening or specific diagnostic purposes, the basic approach should be the same. Many of these tests have the potential to expose their patients to additional risks, and clinicians should ask themselves if the proposed tests are necessary. In the end, the alternative approach may be beneficial to the patient in more ways than one.