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I'm told this is why doctors don't typically go on "fishing expeditions". They could order an array of tests every time you go for a checkup. But given the fa
by adwf 13y ago
I'm told this is why doctors don't typically go on "fishing expeditions". They could order an array of tests every time you go for a checkup. But given the false positive rate combined with only vague symptoms (eg. occasional headache, stomach ache, joint pain), which could be almost anything - it's frowned on to go looking unless there are very specific symptoms or large degrees of discomfort/pain.
Of course in a health system where every check and scan can involve large amounts of profit...
- hashmymustache 13y agoDefinitely true that labs/imaging without good pretest probability or indications are frowned upon. The check everything mentality, at least to me, seems to reflect liability concerns for serious missed diagnoses as opposed to profit scheming. Many of these fishing expeditions are in emergent care settings where the hospital ends up eating most of the cost.
- adwf 13y agoYeah I was probably being a little snarky there. I'm sure that the vast majority of doctors, even in profit-making systems, are just trying to do the right thing. But there's no reason the less scrupulous ones couldn't be doing it for both reasons ;)
- Amadou 13y agoI'm sure that the vast majority of doctors, even in profit-making systems, are just trying to do the right thing. This 2009 article looks at what happens when doctors invest in medical facilities. It doesn't even have to be overt, it's just an incentive that can warp the perspectives of even the most patient-focused doctors. McAllen Texas has the 2nd highest medicare costs in the country, but the next town down the road is much closer to the norm. Guess what the difference is... http://www.newyorker.com/reporting/2009/06/01/090601fa_fact_gawande?currentPage=all http://www.newyorker.com/reporting/2009/06/01/090601fa_fact_...
- deleted 13y ago[deleted]
- anigbrowl 13y agoArguably this attitude is a contributor the problem of antibiotic resistance.
- DrewAllyn 13y agoFalse positives can have a ton of very negative effects. There is the monetary cost of further testing, which can be high depending on what is being tested for, and most importantly, telling a bunch of people that they have some particular disease when they don't is really bad. They may become more stressed, which can bring about a whole host of problems, people might start telling family members, and start getting their affairs in order, they might make different financial decisions based on these false results. And its actually very difficult to administer these tests in a way that doesn't results in way way more false positives than true positives.
- gohrt 13y agoFalse positives (and even true negatives) have non-zero cost. http://articles.mercola.com/sites/articles/archive/2013/03/02/3d-tomosynthesis-more-risky.aspx http://articles.mercola.com/sites/articles/archive/2013/03/0...
- ig1 13y agoThis is actually a stats 101 issue. Imagine that most tests only had 5% false positive rate, then if you took 20 tests then chances are at least one of those is going to give you a false positive.
- renata 13y agoTo be pedantic on stats 101, the chance of having at least one false positive is actually (1 - (.95^20)) ~= 64%, because it's 1 - the probability of every test not having a false positive.
- niels_olson 13y agoMan, that's not pedantic. That's the critical insight that demonstrates someone is competent to talk about stats at all. I wish more people would take the time to point that out when people make the OP's error.
- ScottBurson 13y agoIn fairness, ig1 just said "chances are...", meaning the odds are better than 50-50.
- rmrfrmrf 13y agoThank you.
- ig1 13y agoYes. But no-one is going to remember "solve x for (1-(.95^x)) > 50" the purpose of the 95% & 20 is that it's easy for people to remember.