7 ms·
You are incorrect. All kinds of "shotgun testing" (i.e. indiscriminate testing for everything like you recommend) have been studied, and proven worthless at be
by paviva 10y ago
You are incorrect.
All kinds of "shotgun testing" (i.e. indiscriminate testing for everything like you recommend) have been studied, and proven worthless at best, and more often than not, actively harmful.
First, there is the issue of tests' limitation, and extremely low predictive power. For instance, if testing positive on A makes its 20 times more likely that you'll get B, and the prevalence of B is 1 out 1000 000 in the general population, your own personal risk remains low enough that nothing has changed -- except that you will panic and do unnecessary interventions to reduce this risk. That is precisely the reason tests are asked when you already have symptoms, so if you're pretest probability of disease is 10%, a positive test results means you most probably have it, and it is worth doing something about it.
Second, all known treatments (including "preventive" ones) carry non-zero risk. When you don't have symptoms, whether or not you test positive, your risk of dying from a disease remains lower than dying from an intervention to prevent the disease -- thus, you gain nothing by testing.
Let's take for instance a 40-yo female who gets an ECG done for no good reason. It shows signs of heart disease, which could be a variant of normal, or a sign of a disease. The lady is worried, so she goes on with a stress test just to be sure. She tests positive (a sizeable proportion of those tests are false positive for multiple reasons), so she decides to go on and follows up with a coronary angiogram to see if there's any blockage. Angiogram is normal, but, a coronary is perforated during procedure (1/10 000 risk), and she dies on the table, when she never had any health problems beforehand. This kind of stuff happens all the times.
Finally, from an ethical stand-point, as long as healthcare -- and the individual's stupid testing choices -- are paid for collectively, individual choices should be severely restricted.
If we were in a country without any kind of state-sponsored healthcare, where you'd get to pay for any self-harm from your own pocket, I'd argue for free-for-all testing for anyone without any oversight.
- bobowzki 10y agoI'm a physician. This is the thing most people don't get about tests. It's tiring to see these startups with their flawed agenda.
- petra 10y agoBut what if we could redesign the healthcare systems, in a way that doesn't expose people to all their test results , only critical ones, but gives the doctor/system that data in order to enable to better watch their patient ? Would that be useful?
- bobowzki 10y agoWell, it's a good point but how do you decide what's critical? To answer my own question; I believe the future lies in machine learning algorithms processing symptoms and tests (I guess a symptom is also a test in the sense that it's the answer to a question). Most of the times there's also not a simple answer to be found . The right answer depends on many factors including the capabilities of your hospital/country/economy and the state of science.
- petra 10y ago>> I believe the future lies in machine learning algorithms processing symptoms and tests At the core you're still left with the question - tell your patient directly results of a statistical analysis of a few possibilities and options - and often see him take the wrong one, or guide him through trust(in you or the machine) while not showing him full details. Right ?
- paviva 10y ago> The right answer depends on many factors including the capabilities of your hospital [...] Absolutely ! I'll add that the physician himself is a kind of test, in the sense that his own sensitivity/specificity to diagnosing a disease can be calculated. It is well known -- and I'a argue it's a feature, not a bug --, that the exact same patients with the exact same symptoms will have a different work-up whether he's seen a GP, an emergency physician, or, say a heart surgeon. The reason is pretty simple: because disease prevalence is different in those three practices, the doctor has to order more or less tests to get the same predictive power. E.g., when every patient has heart disease, every ECG change is probably sign of disease, whereas when almost nobody has any heart problems, ECGs are pretty meaningless.
- JamesBarney 10y agoWhile I agree that it's easy to misinterpret statistics. And I agree that sometimes the government needs to restrict freedom of choice to nudge the collective good for the betterment of society. I just can't see testing as one of those issues compared to the other health issues of society, like overwork, junk food, sedentary life styles etc...
- TeMPOraL 10y agoNah, 'paviva is right. Unnecessary tests are a problem, and you can put them in the same bag as hypochondria and WebMD abuse in terms of things where our brain's heuristics and cutting corners in evaluating probabilities start to work against us. > compared to the other health issues of society, like overwork, junk food, sedentary life styles etc... You can always find bigger issues. But given that there are startups and big companies that try to solve the issues you mentioned with spurious, half-assed, unscientific pseudo-tests (yay "wearables", yay "Internet of Things"!), it's even more worrying, because suddenly testing abuse may get coupled with the problems above.
- bobdole1234 10y agoThis is like the people talking about throwing away their scales or only weighing themselves every few weeks while trying to control their weight. The solution isn't fewer data points, it's to collect the data frequently and rigorously, and the post process it into a trend. That's how testing should be done. You get a long series of measurements that are post processed into a coherent picture of the reality.
- TeMPOraL 10y agoNo, this is like people telling others to weigh themselves only once a week - because they know that members of the general population can't be bothered to understand "mathy" concepts like running average, or (gasp!) low-pass filter. It's recommended because otherwise a lot of people end out freaking out over noise in the data. And this is exactly the topic here - laymen freaking out over data they're not equipped intellectually and emotionally to comprehend. Now the other point - that moar data is always better; in principle, yes, if you follow rigorous rules about collecting, analyzing and integrating it into the existing body of evidence. Which is not what usually happens outside research conditions. As you said, > [the solution is] to collect the data frequently and rigorously, and the post process it into a trend. The thing is - we've having big problems with the "rigorously" part, as well as no-bullshit post-processing. The current wave of companies selling "health" sensors ain't helping - they push on frequent collection in a totally non-rigorous way, using half-assed measuring equipment. And giving that data to normal people first (besides taking it and monetizing it), many of whom will obviously be freaking out. This is not helping to form "coherent picture of the reality" much. It's just helping those companies line their pockets.
- bobdole1234 10y agoThe person you're replying to isn't incorrect. He was saying that having few tests that your treat as predictive isn't as helpful as a long line of tests that are interpreted over time as predictive. Your example is someone taking a test and immediately moving ahead with treatment. Not someone taking a test, noting the result was interesting, and then takes more tests over the next few weeks, months, or years to confirm the results were something to be concerned about. If the tests are cheap and simple to run, there is no reason to EVER act on the basis of a single data point.
- paviva 10y agoYou have no clue, sorry.