You would think that you can never have enough information about your health. Barring financial considerations, the more testing the better.
That actually is not true. In some situations, too many diagnostic tests are being run, and it hurts rather than helps the patient. American Medical News has an article about this
Lab tests go under a critical microscope Experts point out that good tests used badly can lead to bad medicine. Victoria Stagg Elliott. Nov. 1, 2004. www.ama-assn.org/amednews/2004/11/01/hlsd1101.htm
They offer several good examples.
- Dialysis patients will often show abnormal results immediately post-dialysis, but these values almost always normalize without intervention.
- A positive herpes test cannot easily distinguish between type 1 and type 2 herpes, but a positive result without drawing such distinctions could result in serious and unnecessary personal difficulties.
- A slightly abnormal antinuclear antibody test may indicate nothing, but patients who surf the Internet may believe that they have lupus or another serious disease.
The article suggests ordering specific tests rather than an entire panel. Why include tests that you know provide no useful information but which might unduly increase anxiety in your patients?
Gina Kolata wrote an excellent article about the problems with unnecessary tests for the New York Times (Annual Physical Checkup May Be an Empty Ritual, August 12, 2003). Most of the tests done at your annual physical exam have no support in the literature, but patients still expect these tests. She has a marvelous story about a patient with a laundry list of tests that she wanted.
Even doctors who know all about the evidence-based guidelines for preventive medicine say they often compromise in the interest of keeping patients happy. Dr. John K. Min, an internist in Burlington, N.C., tells the story of a 72-year-old patient who came to him for her annual physical, knowing exactly what tests she wanted. She wanted a Pap test, but it would have been useless, Dr. Min said, because she had had a hysterectomy. She wanted a chest X-ray, an electrocardiogram. Not necessary, he told her, because it was unlikely that they would reveal a problem that needed treating before symptoms emerged. She left with just a few tests, including blood pressure and cholesterol. Dr. Min was proud of himself until about a week later, when the local paper published a letter from his patient - about him. "Socialized medicine has arrived," she wrote. Admitting defeat, he called her and offered her the tests she had wanted, on the house. She accepted, Dr. Min said, but after having the full physical exam, she never returned.
I discussed the problems with whole body scans, pap smears for women without a cervix, and prostate specific antigen tests in earlier web log entries.
The real reason that people do not appreciate the problems with too many diagnostic tests is that they do not understand that there are costs associated with a false positive finding: the preventable anxiety that a false positive test produces, the cost and risks associated with additional testing, and sometimes the unnecessary medical treatments given for those who are falsely labeled as being sick. When the prevalence of the disease being tested for is low, then this problem is magnified because the false positives greatly outnumber the false negatives.
You can find an earlier version of this page on my original website.