Saturday, August 21, 2010

Medical Information and Mis-information (Part 1)

I have always been struck by the number of medical "facts" that my patients "know" that just aren't so (e.g. there is no evidence that an hour of sleep before midnight is equal to two hours of sleep after midnight), so I thought I would devote this blog to a discussion of such "facts".

I first must explain the difference between correlation and causation. Often medical epidemiologists will examine a homogenous group of patients with disease X, to see what , if any, their life styles have in common compared to patients without disease X. However there will always be some accidental correlation: if you shoot at a tree you are bound to hit a leaf, but unless you specify in advance what leaf you plan to hit, this information is of no use. Similarly, in a given state, some county will have the highest prevalence of breast cancer, and another will have the lowest, but I wouldn't recommend rushing to move to the county with the lowest incidence. So although it appears epidemiologically that females who have pet cats or kittens under the age of 16, or who live north of the Tropic of Capricorn or south of the Tropic of Cancer (i.e. not in the tropics) until age 16 have an increased risk for developing multiple sclerosis, we should treat this correlation as a hypothesis to be proved. Now we have to do the forward experiment, and see the effect of giving or not giving kittens to matched young girls (which is, of course, not ethical). Similarly, there was a great hooraw in the news when it was found that coffee drinkers had a greatly increased risk of getting a heart attack compared with non-drinkers, until it was realized that many more coffee drinkers smoked cigarettes than did non-smokers. Also, although low fat diets seem to be epidemiologically connected to lower breast and colon cancer rates, a five-year forward study of females placed on a low-fat diet showed no diminution of cancer incidence. As I tell all my patients ALWAYS WAIT FOR THE SECOND AND CONFIRMING STUDY.

Some of you may not agree with my statements, but again I must emphasize that if you think my statement is incorrect, you should find a published refereed research paper (you can check through PubMed) that disagrees with my statements. In fact this is the trouble with all newspaper stories, that they quote from and interpret the research study, but never include a link where you can read the original research and decide for yourself. You should also beware of all statements made at scientific meetings, since until they are published they have never been reviewed for accuracy.

1) The recommended maximum pulse rate for efficient exercise is a fiction. The study group was young healthy men, and the 80% was pulled from God knows where. When Bjorn Borg won the French Open, his resting pulse was 34 (similar to many marathoners). If he ever tried to get his heart rate up to 0.8x(220-age), he would have either failed or died trying.

2) Where is the evidence for waiting one hour after eating to go swimming?

3) What is the scientific basis upon which the government specifies the minimum amount of square feet an egg-laying hen should have? Dr. Kandel was fortunate that when he did his Nobel prize-winning memory experiments on Aplysia, the government didn't care how many snails he kept in a box, or how often or what he fed them.

4) For any children reading this, it is not true that if you swallow watermelon seeds you will grow a plant in your stomach.

5) Barry Bonds was indicted for perjury for denying using performance-enhancing drugs. Steroids may bulk you up, but I know of no medical article that demonstrated that taking steroids improves your baseball performance. It shouldn't matter what we think, what the government thinks, or what Mr. Bonds thought. If you deny an impossibility, I don't see how it is perjury. (When I went to college my performance-enhancing drugs were a cup of Choc-Full-O-Nuts coffee and two of their brownies.)

6) For years, heavyweight fighters and other athletes were told not to have sex the night before a crucial game. But Joe Namath, Mickey Mantle, and other top athletes have told us that this is not true either (at least it wasn't for them) and beer helped Bobby Lane, the former Detroit Lions' quarterback. Maybe that's why Tiger Woods is having trouble winning now.

7) Radiation can be used to kill virtually ALL germs, eggs and insects. We could safely sterilize our food supply and avoid disasters such as the egg-borne salmonella epidemic, the hamburgers that carried E. Coli, and the lettuce that carried hepatitis. But there is such an ingrained fear of the effects of radiation that even though it is only the food that is irradiated, and there is no residual radioactivity in the food, public opinion prevents Congress from permitting this, let alone requiring it.

8) There is no evidence that colonoscopy reduces the incidence of colon cancer more than rigid sigmoidoscopy does, but since it seemed "obvious" that examining the whole large bowel would produce better cancer prevention than a partial examination, a comparison study of the two was never done. But if colonoscopy were a drug, the FDA would have required a comparative study with cancer or pre-cancerous polyps as an endpoint.

9) Lately, dermatologists have been telling my patients that the growth they removed is "pre-cancerous". That is a ridiculous statement. Your whole body, including your skin, is "pre-cancerous". The medically correct term for such a growth is "not cancer".

10) How often should you have a mammogram, stool for blood, pap smear, etc. No one knows!
Cancer has occurred between annual screening tests. We doctors sort of pull numbers out of the air, modified by what the insurance companies will pay for. If Medicare only pays for cholesterol profiles every 4 months, then that is what we recommend. But maybe you should have a mammogram every six months, or every three. Maybe men over 50 should have a stress-thallium test of their heart every three months, or maybe an echocardiogram every month.

11) Medicare usually does not pay for screening tests. So if a doctor thinks you have a thyroid problem, and he/she puts down "possible thyroid problem", then MCR will not pay for it, and you will probably refuse to have the test done, not wanting to pay for it yourself. So we put down 244.9, which is a thyroid condition, to have MCR pay for the test. Similarly 780.79, "general fatigue", is an acceptable diagnosis to test for anemia with a CBC. On occasion, doctors have even used 799.99, "unknown disease", because we all have at least one of them (which is generally found at autopsy). So we tell all our MCR patients to ignore any diagnoses, and that we put down "Brain tumor" to get their MRI of the brain paid for by MCR or their HMO.

12) How does anyone know what babies want or need? You can't ask the babies, and no eighteen-year comparative studies are done. Right now playpens are out of favor, and we still have no agreement on how long a baby should be left to cry until being picked up. We still argue whether babies' food allergies are reduced or increased by early exposure to proteins. Despite the existence of cat-scratch fever and toxoplasmosis, we still permit kittens and cats to be around pregnant women and new-born babies. I might also mention that dander (cat saliva applied by licking to cat fur) helps induce bronchospasm and possible asthma in humans of all ages, and some states still permit children to keep turtles as pets despite the fact that they are known carriers of salmonella.

13) Medicine can be counter-intuitive: one way of reducing the incidence of calcium kidney stones is by INcreasing the amount of calcium in the diet (and thereby complexing oxalate in the gut and keeping it out of the urine).

14) Speed kills. During the Carter administration, with a maximum highway speed limit of 55 mph, traffic fatalities per mile traveled decreased, only to increase when 65 mph was reinstated. Because of kinetic energy, the amount of damage in an automobile accident goes up with the square of the velocity.I am not aware of any auto driver or passenger fatalities occurring as speeds under 35 mph, but we don't want to sacrifice that much time. (We also don't know why in most states when seatbelts were introduced the rate of pedestrian fatalities increased.) You should protect yourself by driving the heaviest car you can, like an SUV, since if you are unfortunate enough to be in an accident, you want the other vehicle to bounce off you, and not to crush you.

15) If you don"t "believe" in sleeping pills, then if you are a woman try OTC Benadryl 25 or 50 mg at bedtime. It is so safe that we give it to pregnant women. A future blog will address medical belief systems. And if you husband doesn't believe in them, hide them from him. It's your body.

16) There has been no study to show that if you post the number of calories next to food that people will lose weight.

17) The FDA does not have the authority to clear or license any new surgical procedure, including robotic surgery. Any surgeon can do any surgical procedure if he/she can convince the patient to permit it. I have read articles that it takes 150 to 250 operations to become proficient, for instance, in robotic prostate surgery. So don't be the first human on whom your surgeon is doing a new procedure.

18) The only way to find out who is a good surgeon, or the ability of any other doctor is to do as I did, and ask the residents who work with them. The residents see it all: in the operating room, post-op care, medical diagnosis and treatment, etc. If you ask your friends, all you get is their opinion. Even the published ratings are a joke, as any doctor will tell you. And hospitals can improve their open heart surgical death rate by not operating on the sickest people. (As I recall, there was an Op-Ed piece in the NY Times about 10 years ago by a columnist who had a very difficult time trying to find a cardiac surgeon who would operate on his mother for this very reason.)

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