Ignorance, Knowledge, and Bliss; Not Always Obvious

I’ve just finished sitting through a wonderfully aptly named lecture: Probability and Sadistics, in which, among other things, we learned (again) that the utility of various clinical tests depends at least as much and generally more on the patient and condition involved than on the specific test itself. From stress tests to mammograms to PSAs, the relationships of true and false positive and negatives, positive and negative predictive values all hinge on the prevalence of disease; or how likely is it that a given condition is present before you even do the test. Lots of times when you crunch those numbers, the best answer is not to do the test. Perhaps not unsurprisingly, that tends not to go over real well with patients.  I think we do too many mammograms. Many people agree with me. I spend lots of time talking with my patients about why I don’t think they need a mammogram. Many women understand, but many others don’t. So I order it. I try not to do routine PSAs. I preface the blood draw with a discussion about how he’s more likely to die with rather than of prostate cancer, and about the risks of incontinence and impotence as complications from its treatment. It’s often enough to talk them out of it, though not always. I try so hard not to do stress tests unless I’m really worried about heart disease. Note that it has to be ME who’s worried about it. Just because the patient is worried doesn’t impact the decision all that...
Source: Musings of a Dinosaur - Category: Primary Care Authors: Tags: Medical Source Type: blogs