Broken Alarms and False Alarms in Medical Testing — the Swine Flu Problem

Swine flu testing is the latest example of an important issue for informed patients. Patients need to understand that some medical tests are valuable if there is a “positive” finding, but not much good at all if they are “negative.” The problem is that the test is “insensitive,” which means a negative result can miss the disease that’s really there — a “broken alarm.”

For swine flu, in every 100 patients who actually have flu, the various brands of “rapid flu” tests will have a “positive” result (meaning the patient has the flu bug) for as few as ten of the 100 patients, or as many as 69 of the 100 patients. Even with the higher accuracy, that means that a lot of patients are being missed by these “rapid flu” tests. These statistics come from a New York Times article quoting newly published studies and experts in the field including the Centers for Disease Control and Prevention.

A CDC official told the Times:

“We’re saying you need to understand the limitations of these tests,” Dr. Timothy M. Uyeki, an author of the C.D.C. guidance, said in an interview. “The clinician should not base a decision to treat or not treat on the basis of a negative result.”

Another classic example of an “insensitive” test is the “hemoccult” test for hidden blood in the stool. If it’s positive, you need further workup. If it’s negative, it doesn’t give you a clean bill of health for colon cancer. That’s why the standard screening test for colon cancer is a colonoscopy, which looks at the entire length of the colon with a video camera.

My book “The Life You Save” has a chapter about understanding medical testing and why you cannot necessarily rely on a negative test result.

The point is: A negative result doesn’t mean you have a clean bill of health. Sometimes you have to pay attention to other signs and symptoms.

Patrick Malone & Associates, P.C. listed in Best Lawyers Rated by Super Lawyers Patrick A. Malone
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