Posted on 07/12/2005 9:58:05 PM PDT by NormsRevenge
CHICAGO - Here's some medical news you can trust: A new study confirms that what doctors once said was good for you often turns out to be bad — or at least not as great as initially thought.
The report is a review of major studies published in three influential medical journals between 1990 and 2003, including 45 highly publicized studies that initially claimed a drug or other treatment worked.
Subsequent research contradicted results of seven studies — 16 percent — and reported weaker results for seven others, an additional 16 percent. That means nearly one-third of the original results did not hold up, according to the study in Wednesday's Journal of the American Medical Association.
"Contradicted and potentially exaggerated findings are not uncommon in the most visible and most influential original clinical research," said study author Dr. John Ioannidis, a researcher at the University of Ioannina in Greece.
Experts say the study is a reminder to doctors and patients that they should not put too much stock in a single study and understand that treatments often become obsolete with medical advances.
"A single study is not the final word, and that is an important message," editors at the New England Journal of Medicine said in a statement about the study.
The refuted studies dealt with a wide range of drugs and treatments. Hormone pills were once thought to protect menopausal women from heart disease but later were shown to do the opposite. Contrary to initial results, Vitamin E pills have not been shown to prevent heart attacks.
Contradictions also included a study that found nitric oxide does not improve survival in patients with respiratory failure, despite earlier claims. And a study suggested that an antibody treatment did not improve survival in certain sepsis patients; a smaller previous study found the opposite.
Ioannidis acknowledged an important but not very reassuring caveat: "There's no proof that the subsequent studies ... were necessarily correct." But he noted that in all 14 cases in which results were contradicted or softened, the subsequent studies were either larger or better designed. Also, none of the contradicted treatments is currently recommended by medical guidelines.
Ioannidis' study examined research in the New England Journal of Medicine, Lancet and JAMA — prominent journals whose weekly studies help feed a growing public appetite for medical news.
Not by accident, this week's JAMA also includes a study contradicting previous thinking that stomach-lying helped improve breathing in children hospitalized with acute lung injuries. The new study found they did no better than patients lying on their backs.
Dr. Catherine DeAngelis, JAMA's editor, said she included the study with Ioannidis' report to highlight the nature of medical research.
"The crazy part about science and yet the exciting part about science is you almost never have something that's black and white," she said.
Ioannidis said scientists and editors should avoid "giving selective attention only to the most promising or exciting results" and should make the public more aware of the limitations of science.
"The general public should not panic" about refuted studies, he said. "We all need to start thinking more critically."
DeAngelis also noted that the media can complicate matters with misleading or exaggerated headlines about studies.
Ioannidis said that the studies most likely to be contradicted later were what scientists call nonrandomized studies. These are often based on observations of patients' lifestyles rather than on results from a drug or other intervention assigned by researchers.
___
Examples of studies later refuted or watered down by subsequent research, according to a report in Wednesday's Journal of the American Medical Association.
_Hormone pills protect menopausal women from heart disease. A larger, more rigorous Women's Health Initiative study later found the pills increase actually heart disease risks.
_Vitamin E pills protect against heart disease. A more rigorous study found no such protection.
_Antibody treatment targeting a bacterial poison improves patients' chances of surviving sepsis, a potentially deadly bloodstream infection. A much larger study found no protection.
_Inhaling nitric oxide helps patients with respiratory failure. Larger studies found no benefit.
_Antioxidant substances contained in tea, wine and many fruits and vegetables substantially reduce the risk of heart disease. A later study said the benefit was more modest.
_An operation that clears fat from neck arteries reduces stroke risks in patients without symptoms. A subsequent analysis found more modest benefits.
___
On the Net:
JAMA: http://www.jama.ama-assn.org
Butter
Red Meat
Wine
and soon Nicotine!!!
All so very bad for you...
People confuse "interesting" with "good" and "bad". Don't rush to judgement, is the lesson.
Mc Donalds is good for you. the 1$ menu is the best health food.
I eat lots of fast-food, but only the chicken meals and usually skip the fries. (I think I'm healthy?)
I have always let the "real" study run before even considering the value of a new medicine. If you think about a large study of say 20,ooo subjects and that those results are expanded to a population of 300 million in the U.S. or the 5 billion people in the world the study numbers are insignificant.
I have always let the "real" study run before even considering the value of a new medicine. If you think about a large study of say 20,ooo subjects and that those results are expanded to a population of 300 million in the U.S. or the 5 billion people in the world the study numbers are insignificant.
sorry about the double post, I looked and it wasn't there.
So does this mean, we should do the opposite of what the 'experts' tell us?
It means you should never do what the mass media recommends you do based on some biological or medical study. The data are usually complex and can be analyzed in different ways, while the nincompoop science writers at major media outlets like the New York Times Science Digest report it badly, with bias but without nuance. A lot of times they miss the point or exaggerate the findings because they don't know anything about methodology and statistical analysis.
It means that you shouldn't take most of this stuff seriously unless you read Lancet, JAMA, Nature, Science, Brain, or more obscure scientific/medical journals and have the expertise to figure out what you're really reading. And it means you should use common sense. Eat a balanced diet, don't smoke (or just smoke pipes or the occasional cigar), don't do illegal drugs, take a multivitamin, have a glass of wine with dinner every night, exercise, relax, sleep, have fun, keep tabs on your blood pressure, take prescribed meds, get and stay married, don't take part in Ironman competitions, pray, keep pets, etc. etc. etc.
"Experts" are under tremendous pressure to publish and get their names out there. Otherwise they stuck actually having to practice medicine.
Eating less and exercising more would do more for health in this country than any medical breakthrough. "Off your seat and on your feet," as my mother used to say. Not only would this empty hospital beds and medicine cabinets, but it would bankrupt the weight-control industry that counts on the fat of the land for their profit. It means limiting portions and limiting the time spent in front of the TV and computer, but it's the only way to live longer.
So, what worked for all my relatives and ancestors who lived into their upper 80's and 90's is okay? Live moderately, eat a balanced diet and take Sunday off when possible to de-stress?
With the occasional martini, sounds good to me.
If they are referring, as I think they may be, to "TFPI" (tissue factor pathway inhibitor) which is an antibody that inhibits blood coagulation (one of the final "symptoms" before death in sepsis) it certainly was an expensive lesson. It was very impressive in preclinical trials in monkeys where (given immediately) it protected against sepsis caused by massive IV doses of E. coli. Trouble was, the causes of human clinical sepsis are more complicated and diverse and TFPI didn't do any good against some of them. And timing is everything - by the time you diagnose the causative agent in sepsis, it may be too late for any treatment to work. So clinical trials were pure hell. Half the time you realized after the fact that the patient was inappropriate for the treatment, but by then they were dead.
In addition, as a wise old statistician once told me "if you need statistics to tell you if your treatment worked, you probably should do the experiment over again anyway".
Which is why one should always vote against something before voting for it.
I so agree with your tagline! I never do what the mass media recommends; just my obstinate nature I guess. I just hate getting into spats with my family doc, when I argue against the 'latest' expert opinions on things. Expert, of course, is defined as: ex= has been, pert(spurt)=drip under pressure.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.