As a physicist as well as a practicing physician, I am always disturbed by medical statements that have no basis in experimental or clinical fact. Some statements are considered to be "obvious", some are practicalities stated by the government, and some have the inertia of years if not centuries of belief. I have always told my patients that if any doctor (including myself) makes a medical statement of "fact", they should ask the doctor where they can read about it. OTOH, if the doctor says "I believe", or "I feel", then take the advice with at least 10 grains of salt. It is, of course, more difficult when your spouse tries to impress a "fact" on you, and you can't really answer "where did you get your medical degree"?. One of my patients brought in a paragraph cut out from a magazine which explained her disease and treatment in detail. Since the article was taken from the "National Enquirer", I told her that I was not a specialist in this particular field, and she needed to consult a specialist. Now that we have the internet, I often have to "unlearn" a patient before I can "learn" him or her. BTW, the only source you should trust about cancer is the web site of the National Cancer Institute. All other institutional websites have an institutional bias. For instance, the chairman of one teaching hospital wrote a book about how the only treatment for prostate cancer is surgery, so few if any urologists at that institute would suggest either radiation or watchful waiting. This raises another point: if you want a second opinion, always go to a different institution, since there is real institutional bias. 30 years ago, when I trained, I was told that Cornell/NY Hospital only ran digitoxin levels, and not digoxin levels, so if you were an intern at NY Hospital, you had to use digitoxin to treat your heart failure patients. Similarly, at Columbia, the ANA was run daily in the lab, and the LE Prep only weekly, so that even though the LE prep was a more definitive test for lupus, all the interns had to screen with the ANA. As a final example, the body runs on thyroid hormone. (Let's forget T3 for the purpose of this discussion.) So the real test for hypo or hyper thyroid state was free T4. However, this was a radioimmunoassay , and very expensive, so we were all taught to screen with the TSH, a pituitary hormone, and only do a free T4 if the TSH was off. This meant that the patient had to be stuck twice for blood, and the correct diagnosis was delayed.
Brief joke: The way opticians charge for eyeglasses is as follows: When they give you your eyeglasses, they say "That will be $300". If you don't flinch, they add "That's for the frames. The lenses are another $300". If you still don't flinch, they add "Each".
The following are some of the medical "facts" that are not based on clinical studies:
1) Marijuana is classified as a Class I drug by the FDA, which means "no possible clinical benefit or use". Nevertheless, the U.S. government grown marijuana plants in Lexington, Ky., for those patients whose glaucoma can only be successfully treated by smoking marijuana.
2) Ecstasy, the pleasure drug used at raves, is also classified as Class I. However, at least eight psychiatrists around the country have special license to use Ecstasy on otherwise intractable schizophrenic patients.
3) Shades of "One Flew Over the Cuckoo's Nest": A physician in Europe received the Nobel Prize in Medicine for "proving" that pre-frontal lobotomies "cured" schizophrenia. Not so.
4) The BMI is touted as calculating your IBW, or ideal body weight for your height. This number has no basis in fact, and is merely a derived average. No one has shown that patients with a "normal" BMI live longer, and in fact a recent study in Lancet disproved this. Also, the IBW in the Metropolitan Life Insurance tables was specifically derived for patients wearing shoes.
5) Ideal pulse at workout = 0.8x(220-age). This is also a purely fictional number derived from healthy young men. In fact, the greater your aerobic conditioning, the lower is your resting pulse and peak pulse. Just ask any marathon runner.
6) Eating sugar causes diabetes. Just because diabetics have high sugars, it is not true that eating sugar causes it.
7) Too much salt causes high blood pressure. Another canard, unless you are a specially genetically formed lab rat. Normal kidneys can always clear salt. But because of this belief, many of my golfers get faint and dizzy by the 13th hole, because they sweat salt plus water, and drink only water, and dilute down the salt levels of their body. Salt in the blood defends blood pressure. The salt content of blood is approximately equal to a 50/50 mix of water and Gatorade, which is how the football coach of the University of Florida developed Gatorade.
8) For some reason, if you go to donate blood at the Red Cross, they will refuse you if your blood pressure is "too high". This is very odd, because 100 years ago, before we had any useful anti-hypertensive medicines, the only treatment that successfully lowered blood pressure was bleeding with leeches.
9) When I went to school the food triangle had an apex and a base, and one was protein and the other was carbohydrates. Now the food triangle taught in school is exactly the reverse. Who is/was right?
10) Labeling calories probably does not lead to weight loss. Taco Bells in LA have had to do that for the past 13 months, but the total calories consumed by the average patron did not change.
11)Question: If the real reason for raising the drinking age to 21 was to keep drunk teen-age drivers off the road, why not let teenagers who do not have a driver's license drink?
12) Why are all addicting foods vegetables (nicotine, alcohol, opium, cocaine, etc.)?
13) The "normal" fasting blood sugar has been lowered from 140 to 120 to 110 to 100, but no one has shown any medical benefit or reduction in diabetic morbidity from these lowered definitions. OTOH,. if your FBS is 110, your life insurance premiums will now be higher.
14) Medicare Part D now only pays for generic versions. However, many doctors are aware that for some drugs, especially those that act on the CNS (Ativan, Prozac, Wellbutrin) often only the brand name works. I have similar arguments with drug "management" systems such as Medco, who claim that only their preferred brand of stomach acid suppressant, such as Prevacid works. When I try to tell them that only Aciphex works on my patient, they don't want to hear it, although they know full well that although they have the same endpoint, since the two drugs have different chemical structures one will work when the other will not.
15) I will close with the most common misperception of all, and one that we are all guilty of, and that is persisting in giving medical advice to our loved ones after it is evident that they will not follow it. After you tell a smoker to stop smoking or a heavy diabetic to lose weight more than once, they have received your message. It's not that they don't understand you, it's just that they don't want to follow your advice. And they know their actions may not be logical, but they still refuse. Some patients refuse to have a mammogram, or a colonoscope, or even to see a doctor. Many patients will refuse to follow good advice, even when they agree with it, for various reasons, some of which they do not fully understand themselves. When this does happen, you should stop and ask yourselves if you would follow medical advice that a loved one gave to you if you did not believe in it or did not feel like doing it.