How useful are screening tests in the community?
Inexpensive screenings for carotid and aortic vascular disease are offered in many communities. My patients often ask if it is worth it to pay out of pocket as these screenings are not covered by insurance. There are several problems with mass screenings by any technique. These issues can be summed up below:
- Problems associated with the screening itself. Who is running the screening, and what are their qualifications?
- Is the study done by a qualified and licensed technician and supported by a laboratory that is certified by health care insurers?
- How standard are the tests and procedures being used? Often the technology being used is not as good as the technology that your doctor has access to. Sometimes, the test is experimental (see below)
- The likelihood that the screening is correct. The worst results of screening occur when the answer is just wrong. While people are reassured if the test is normal, missing an abnormality because the test is of insufficient quality is a major problem. This is called a false negative. Likewise, a test that suggests an abnormality that turns out not to be there in truth creates a lot of anxiety. This is called a false positive. Getting it right (called accuracy) is what is most important. We test this, and report it in hospitals and laboratories. Are the same methods, equipment and personnel being used at the screening
And what happens as a result of the screening. Who will receive the results, and what is the availability of qualified counseling about the clinical importance of the results? Each year, several patients enter my office with anxiety over various tests that they have undergone. Some of these tests are helpful. I had one patient who underwent a “screening” electron beam computerized tomographic scan (called EBCT because it is such a mouthful) that demonstrated calcium in her coronary arteries. It was this $4,000 test that got her to stop smoking, though, it also made her think that she needed heart surgery. On the other hand, I have had countless patients come in with results that duplicated what was previously known, or that were totally worthless (hair analysis, etc.).
Problems related to the group being screened. The likelihood of abnormalities affects the accuracy of the test. An abnormality is very unlikely to be present when looking for aneurysms in teenagers. Thus, an abnormality found in this group is likely to be an error. Screening 95-year olds for carotid disease may find a lot. But given the future life expectancy that is limited, an abnormal finding may cause more anxiety and testing than would benefit the patient.
So in summary, the answer to screenings that may cost you money: buyer beware. Caveat: free screenings supported by major medical societies and associations are usually quite beneficial, and avoid most of the above problems. The purpose of these screenings is to catch problems in patients who are not obtaining regular medical care, for whatever reason.