Prevention---science vs. nonsense

This is a cross-post from Science-Based Medicine. Go there! --PalMD

There are many ways in which cult medicine believers try to insinuate themselves into the health care system. As Dr. Gorski has pointed out, "prevention" is one of their metaphorical feet in the door. The cult medicine literature often says things like, "mainstream medicine is fine for treating acute illness, but what we do is prevention." What they often leave out is the question of what "prevention" means, what the data on prevention is, and how to properly approach prevention. It's likely that one of my co-editors will touch on this topic in a bit more detail, but let me give you an introduction to the topic of prevention.


Prevention is usually divided into three types: primary, secondary, and tertiary.

Primary prevention refers to the prevention of diseases and conditions before their biological onset. Examples of our most successful primary prevention interventions are clean water/sewerage and, ironically, vaccination. I say "ironically" of course because so many of the altmed folks who talk about prevention are anti-vaccine.

Secondary prevention refers to the search for diseases that have not yet progressed to the point of causing overt disease, and intervening to prevent overt disease. This includes things like Pap smears, which look for early cervical cancers (which could have been primarily prevented by vaccination), mammography, which looks for early breast tumors, and colonoscopy, which looks for early colonic neoplasms. Secondary prevention is sometimes used synonymously with "screening".

Tertiary prevention refers to the prevention of progression of and complications from existing disease. For example, retinal and foot exams in diabetics prevent blindness and amputation very effectively.


We know quite a bit about prevention. As I mentioned, vaccination is a very powerful tool of primary prevention. Let's take another example, coronary heart disease (CHD). We know quite a bit about primary and secondary prevention of this disease, one of the top two killers of Americans. For example, quitting smoking drastically reduces a person's chances of developing CHD. Controlling blood pressure and cholesterol also drastically reduces the risk of developing CHD. Physical activity and a lower calorie and lower sodium diet lower the risk of developing CHD, although using it as a sole intervention is not always adequate.

Secondary prevention is another area where science has taught us a lot. We have excellent data on the benefit of certain drugs and certain blood pressure and cholesterol parameters in preventing progression of CHD. Statin drugs used to lower cholesterol have been shown consistently to significantly lower the risk of cardiovascular events. We are getting quite good at this type of secondary prevention. So-called lifestyle changes also play a role, but the size of their effect is likely much less than that of medical intervention. Still, the two used together can be very effective. Much of the data on lifestyle modification alone are from very small studies, and the data are not nearly as strong as that for quitting smoking, controlling cholesterol, or controlling blood pressure.

Tertiary prevention has been very successful. For example, diabetics have a very high rate of lower extremity amputations. Simple foot care programs can prevent most of these.


The alternative medicine community gives a lot of lip service to "lifestyle changes" and prevention, but data from them is very hard to come by. For example, the U.S. Preventative Services Task Force has dozens of evidence-based recommendations on prevention. The National Center for Preventative and Alternative Medicine (NCCAM) has a page on cancer prevention, but most of it is about studies that have not yet been done, or interventions that have been unsuccessful.

The study of prevention is a science---we can't just make it up as we go along. When we give people recommendations on preventing disease, we better know what we're talking about. For example, beta-carotenes where thought to have anti-oxidant--and therefore positive--health properties. It turns out that beta-carotene supplementation may actually increase the risk of some cancers.

When someone talks about prevention, making pretty-sounding promises isn't enough. They better make sure they have the data to back it up, or they may end up killing people.


More like this

I couldn't make it a week without talking again about Newstarget, home of Altie-med uber-crank Mike Adams. This time, they caught my eye with a surprising read of this large study of the antioxidant vitamins C and E. Jack Challem, writing for Newstarget, tells us the good, but hidden, news from…
First, I'd like to thank everyone who participated in the naturopaty primary care challenge. It was far more successful than I could have hoped. A number of naturopaths and their supporters responded, most of them quite rationally. It takes guts to walk into the fire. It also takes fanaticism…
I'm a primary care physician. What I, other internists, pediatricians, and family medicine docs do is prevent and treat common diseases. When we get to diseases that require more specialized care, we refer to our specialist colleagues. There is a movement afoot to broaden the role of naturopaths…
I was disturbed several months ago when I learned that the director of the National Institutes of Health, Francis Collins, had agreed to be the keynote speaker at the Eight International Society for Integrative Oncology Conference in Cleveland, OH. I say "doubly" disturbed because it disturbed me…

AAARGH!... this is a big bane of contention between me and a certain woo relative. Apparently she wants to use alt-med as a shortcut to avoid the preventative advice from those who were her medical doctors.

A long while ago she complained of constipation... So I told her that walking around the block helped me. I received a nasty glare!

Then she said she found information on an internet forum of all sorts of foods that were bad for her, so she cleaned out her cupboards. But as it turns out, since she hates most vegetables, she did not add the "foods that are good for you" to her diet. The only vegetables that I have seen her eat in any family gathering over the past twenty years have been corn and potatoes. That is it. Nothing green, no peas, no beans and definitely no salad (and doubly no! on broccoli!... oh, and she has never tried my really good double crust pizza stuffed with spinach!).

She did make the mistake of sending me a warning on vaccines. The source was a "" webpage (look up Scopie's Law). I told her I would not endanger my children's health because of what she read on the internet. She then deleted me from her "send obnoxious webpages to" email list.

Then she had a psychotic episode and spent a couple of months in the county psych ward. They made her eat green vegies and take actual walks around actual city blocks, along with taking actual medicine to help settle the chemicals in her brain (they diagnosed her as bi-polar).

Then they released her. Since she was not a danger to herself and anyone else, no one followed up on her. So she decided on her own that a naturapath knew more than the county psychiatrist and stopped taking her real meds. She decided to rely only on the naturapath's prescription of homeopathic remedies.

Which she quickly learned were worthless. She even wrote a long drawn out letter to her parents about this... for which I had to explain exactly what the dilutions used in homeopathy were to her parents during a family Christmas function. Sigh.

Long story, shortened only a bit (it involves temporarily moving to another state, with another stay in a mental ward with a different diagnosis of "schizophrenia")... my relative is back on real medications.

Though we still cannot get her to eat green vegetables and do some actual exercise!

HCN: a double crust pizza stuffed with spinach?! FABULOUS!!! Recipie, plz! scicurious[at]gmail[dot]com.

Get this book:

Complete with illustrations on how to make the stuffed pizza.

I typically triple the recipe (using a Costco size bag of spinach). That way I get the pig deep pizza pan, plus three small ones in cake pans. I then freeze the little ones after baking (one fits inside big freezer zip-lock bag) for later.

"Secondary prevention refers to the search for diseases that have not yet progressed to the point of causing overt disease, and intervening to prevent overt disease."

This statement puzzles me, because in cardiology secondary prevention refers to treatment of people who already are known to have heart disease, in particular to prevent cardiovascular events and other bad stuff. This would include people who are known to have heart disease because, say, they have angina, even though they have not had a first heart attack.

By Marilyn Mann (not verified) on 06 Mar 2009 #permalink

From the AHA/ACC Guidelines for Secondary Prevention for Patients With Coronary and Other Atherosclerotic Vascular Disease: 2006 Update

"Since the 2001 update of the American Heart Association (AHA)/American College of Cardiology (ACC) consensus statement on secondary prevention,1 important evidence from clinical trials has emerged that further supports and broadens the merits of aggressive risk-reduction therapies for patients with established coronary and other atherosclerotic vascular disease, including peripheral arterial disease, atherosclerotic aortic disease, and carotid artery disease. This growing body of evidence confirms that aggressive comprehensive risk factor management improves survival, reduces recurrent events and the need for interventional procedures, and improves quality of life for these patients."

Does secondary prevention mean something different in other areas of medicine?

By Marilyn Mann (not verified) on 06 Mar 2009 #permalink

Of course most of the providers of altmed are frauds through and through, but as far as telling them... well, as Neil Armstrong never said, Good luck, Dr. Gorski. That's the thing though -- people think it's harmless, but even when it is, it's still useless, and people are flushing money down the toilet.


That may be the single best book on pizza I've ever seen -- I've looked through quite a few and almost none of them beat that one. Too bad it's only about Chicago styles -- Bruno wrote the gold standard.