The Problem With False Positives
Following up my post last week about computerized breast cancer screening, I found this report today about the perils of false-positives intriguing. Women who received a positive mammogram for breast cancer - and then later were told the test was wrong, and they don't have cancer - suffered high levels of stress for long periods of time. This was a meta-analysis of 23 different screening studies - meaning it's not a one-off, but much more likely to provide a clear consensus finding. Here's a link to the study abstract. A good reminder that as we embark into an era of more and more screening - for more and more biomarkers and genetic signatures and whatnot - there's a very clear side effect, and a great need to keep the tests' sensitivity and specificity - the accuracy, in other words - as high as possible.(It's not just cancer, false positives are a problem for screening in many diseases).
Which also reminds me of a post by the aforementioned Andy Kessler, who's blogging over at the NYTimes (alas, behind the Times Select wall). His piece today neatly summarizes the argument in his End Of Medicine book - that we're embarking on a new era of high-fidelity screening technologies. If you have Times Select access, look especially, though, at the comments, the first four of which all seem to be from physicians who astutely note the perils of increased screening - both in terms of health care costs and false-positives.