In medicine today diagnostic testing and advanced imaging is readily available and widely utilized in most every clinical setting.  Many physicians have given up the stethoscope and physical exam in favor of an echocardiogram and a CT scan.  Fear of missing something pervades every emergency department and has resulted in hundreds of thousands of unnecessary testing costing billions of dollars in healthcare expenditures.

Of course, the driving causes of increased testing and utilization of advanced imaging are numerous and complex.  Unfortunately, in my experience, the two most common reasons are fear of malpractice litigation and a desire for greater reimbursement.

How do we best determine when to test?

The most basic testing techniques rely on Bayesian statistics — the question to be answered must be well defined and then a clinician must determine a pre-test probability of the presence (or absence) of the disease in question.  The best utilization of a diagnostic test is when a clinician has an intermediate pre-test probability that a particular disease state is present.

If the pre-test probability is low, then there is no need to test.  If the pre-test probability is high, then the clinician should proceed with treatment rather than an additional testing step.

In the case of coronary artery disease, if you have a patient with multiple risk factors and symptoms that are a bit atypical, diagnostic testing with a stress test with imaging makes sense.  If you have a young person with no risk factors, and very atypical symptoms diagnostic testing does not.  In contrast, if you have a patient with classic angina, an abnormal EKG and multiple risk factors you may want to forgo diagnostic imaging and proceed directly to cardiac catheterization.

What are the risks associated with radiation?

In a recent New York Times column, the authors argue that the over utilization of CT scans and other radiation based diagnostic testing results in a significant increased risk for certain types of cancers.  I tend to agree.  The radiation exposure associated with one CT scan is equivalent to more than 500 plain chest x-rays.  The FDA estimates that a patient’s lifetime risk of developing cancer from radiation exposure to a CT scan approaches 1 in 2000.  To place this all in perspective, the survivors of the atomic blasts in Japan were exposed to the equivalent radiation to two CT scans!

In addition to CT scans, nuclear medicine based stress testing in cardiology also exposes patients to large doses of radiation (even more than CT).  These tests are recommended at particular intervals by the American College of Cardiology in patients with known coronary artery disease (CAD) or in cases with suspected CAD with appropriate risk factors and baseline characteristics.  However, just as with CT scans, these imaging tests are often over-prescribed and overused.

What are the root causes for the overuse of diagnostic testing?

Much of the over-testing seen in the US is due to fear of litigation.  Doctors, as a whole, want to do their very best for patients.  When the encounter a patient with a complaint that seems routine, many astute clinicians also think about more serious diagnoses when formulating a differential.  Anecdotes from colleagues where a particular serious diagnosis was “missed” can often lead to unnecessary testing.

Moreover, the trial lawyers and “ambulance chasers” are an ever present thought for many clinicians.  The fear of being sued for missing a lung tumor in an asymptomatic patient can also lead to more unnecessary and non indicated testing.  This phenomenon is yet another important reason that we must pursue tort reform in the US today.

Unfortunately, another reason for overuse of CT scanning and other types of imaging is profit.  Profit and finances have no place in the clinical evaluation of a patient — however, economic realities have blurred these lines considerably in the last decade.  There are some clinicians that put reimbursement ahead of patient welfare.  Abuses such as routine, non indicated imaging for cardiac patients has been declining.  New guidelines and more government and regulatory scrutiny into these types of exams seems to be having a positive effect on reducing unnecessary radiation exposures.

What can we do to advocate for ourselves and our patients?

As a patient, it is essential that you ask your clinician precisely why the test is being ordered and exactly what impact the result will have on your clinical management.  As physicians we must have very clear reasons (and well documented reasons) for ordering tests.  Tests should remain an adjunct to history and physical exam for the diagnosis of disease–not a replacement for clinical experience and expertise.

So, next time you order a test (or your doctor orders a test for you) make sure you take time to understand how the exam is going to impact your course of treatment — if you are at a fork in the road, the best test should determine whether you take the road to the right or the left.

If you and your doctor already know which way to go, the test may only be another chance to “glow in the dark …”

Kevin R. Campbell is a cardiac electrophysiologist who blogs at his self-titled site, Dr. Kevin R. Campbell, MD.