Originally Posted by
jfsully
Well, you are wrong about what most doctors’ daily work entails. Most doctors are not, and shouldn’t be, on TV telling people what is up with covid or health policy.
My point was not that people making policy don’t have to know about things like PPV, it was that public health is a narrow slice of medicine, so finding out that a bunch of clinicians can’t calculate PPV isnt surprising or even worrisome. My comment was in relation to the survey of clinicians linked above.
An example: The PPV of urinalysis for UTI, if I test everyone, is likely to be about 50%. That’s if 1% of the people have a UTI, so this may be high. But in real life I’m not testing everyone, only symptomatic people. Let’s say 75% of the symptomatic people I’m testing have an actual UTI. So the PPV is now about 99%. This test got a lot better when applied to the correct population. So when I order a urinalysis I have no thought of calculating a PPV, nor should I. It simply doesn’t help me in this case. Calculating a PPV isn’t of use to clinicians very often.
So, being a doctor doesn’t necessarily give someone authority to make health policy. But having a medical degree doesn’t disqualify someone either, if they have a public health background.
One other thing to add: while I’m saying that calculating a PPV is not a core skill, there are a group of clinicians who should study up on the concept of PPV, even if they can’t calculate it: the overtesters. I see this mostly in private practice: doctors and NPs who use lots of tests in a futile attempt to reduce the uncertainty inherent in clinical decision-making. Ironically, many patients feel that doctors who do lots of tests are paying close attention and giving them higher-quality care. The opposite is mostly true. Unfortunately, I don’t think that a PPV refresher will solve their problem.