What is a “false-positive” test result, and why should I worry about it?
A false-positive result is one that indicates there’s something wrong when there really isn’t. An example would be a mammogram that erroneously indicates a cancerous lump. This is bad because the tests needed to confirm or deny this condition can cause anxiety, be costly, or have adverse health consequences. You might have to undergo the costs and risks of a biopsy (tissue sampling for laboratory analysis). Unfortunately, some screening tests produce a higher number of false-positive results than the general public realizes. For example, routine blood testing often is misleading. Experts estimate that at least one false-positive result will occur for almost one-half the people having the 12-test set of blood tests, and for two-thirds of those having the 20-test set.
