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Dr. Cohen's Book

September 20, 2005 11:42 AM

I have been reviewing my wife's prescription medicines and am a bit appalled at some of the recommendations of her doctor. She has known renal disfunction and yet was put on Plavix as a preventative against stroke. Renal disfunction dramatically lowers the possibly beneficial metabolite produced from the raw material of Plavix. Among the side effects listed are dizziness (which she is experiencing) and some impairment of her already damaged kidneys.

More troubling is the way the benefits are calculated. Reading the overall mortality risks of placebo, aspirin alone, plavix alone, and plavix with aspirin three conclusions come forth: 1. the risks are very low of mortality, 2. the differences among all four procedures are not significantly different, and 3. the relative risk calculations are without statistical foundation since there are no significant differences among the outcomes even with the large sample sizes of the trials.

Remember sample size is everything in the statistics; large enough samples tend to make everything significant just because of the way significance is calculated. Yet, a Bayesian analysis begins with the prior from the large sample and then the posterior likelihood is caculated from that fairly sharply determined prior (because the sample is large). I haven't done the calculation, but it is easy to see that the posterior is not much different from the prior under all the treatments. The literature that comes with the drug does not do a Bayesian analysis and, instead, promotes the relative risk. This far overstates the benefits, which are questionable given the low overall mortality and the lack of precision in the risk ratio.

We are taking her off Plavix and just using aspirin. I don't think her doctor is aware that impaired renal function diminishes the circulating level of the metabolite or is aware of the minimal differences among the outcomes.

Then comes this brief preview from Dr. Mercola's web site of Dr. Cohen's book on drug-related mortality risk, which is known to be a greater risk than most of the health risks you read about in the paper.

· Evolutionary Fitness

Comments

Posted by: Flower Online [TypeKey Profile Page] at September 12, 2006 7:07 AM

My body is communist. I'm 55, 5'6", 225 lbs and not very strong. And Art is saying get off the stair master???

Posted by: Ron Rizzo [TypeKey Profile Page] at September 11, 2006 7:38 PM

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