Bias etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster
Bias etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster

21 Temmuz 2014 Pazartesi

Ancel B. Keys' critique of "Diet and coronary thrombosis. Hypothesis and fact, by John Yudkin. The Lancet, 1957."

Ancel B. Keys has come in for a lot of flak recently over alleged "cherry-picking" of data for his 6/7 Countries studies. Here's Keys' critique:- "SUCROSE IN THE DIET AND CORONARY HEART DISEASE" of Dr. John Yudkin's "15 Countries" article.

Keys accuses Yudkin of bias, cherry-picking countries that fit his own hypothesis.

Here are some plots from Keys' 11 Countries article.
5-Year CHD cases/1,000 men vs Sucrose %E.

5-Year CHD cases/1,000 men vs Sat Fats %E.

Sucrose %E vs Sat Fats %E.

So there you have it.

15 Temmuz 2013 Pazartesi

I don't believe it.

And neither should you.
From http://workwithstuartchalmers.com/wp/blog/2012/10/02/banners-broker-it-care/
Well, opinions are like assholes, honey. Everybody's got one and everybody thinks everybody else's stinks. The internet is full of opinions. Why should anyone believe anything they read on the internet?

If a writer has (a) qualification(s) in "A", it means that they know something about "A". It doesn't mean that they know anything about "B", "C"....."Z". However, humans being human, they have biases. Writers write in a biased way. Also, readers read in a biased way. Having (a) qualification(s) means diddly-squat. What does mean something, is backing-up what's written with quality evidence. As I have no formal qualifications in Diet & Nutrition, I try to do that as often as possible. When I don't, it's my opinion.

Many people are intolerant of other people's opinions. No wonder so many "fights" break out on forums, message-boards & blog comments. As a writer's qualifications mean diddly-squat, what's the point in arguing about a writer's qualifications? There isn't one! It's an ad hominem fallacy. Bloggers whose blog contents consist mainly of ad hominems & other fallacies are ass hats.

23 Mayıs 2013 Perşembe

Prevention vs Cure, quackery, bias and conflict of interest.

I believe in the maxim "Prevention is better than cure".
Image from www.nationalarchives.gov.uk

Some definitions:

Prevention. Cure. Quackery. Bias. Conflict of interest. Logical fallacies. In the case of the maxim, prevention means hindrance, as it's impossible to 100% stop illness from occurring. To someone who already has an illness, the maxim is obviously moot!

Quackery:

I have been accused of quackery. Despite having provided evidence to refute the claim, the person has refused to retract the accusation or provide proper evidence (other than Logical fallacies) to support it. EDIT: I blocked the person on Twitter. I am no longer on that person's quackery list.

Bias:

A long time ago, I mentioned a study Intensive lipid lowering with atorvastatin in patients with stable coronary disease.

"RESULTS: The mean LDL cholesterol levels were 77 mg per deciliter (2.0 mmol per liter) during treatment with 80 mg of atorvastatin and 101 mg per deciliter (2.6 mmol per liter) during treatment with 10 mg of atorvastatin. The incidence of persistent elevations in liver aminotransferase levels was 0.2 percent in the group given 10 mg of atorvastatin and 1.2 percent in the group given 80 mg of atorvastatin (P&lt:0.001). A primary event occurred in 434 patients (8.7 percent) receiving 80 mg of atorvastatin, as compared with 548 patients (10.9 percent) receiving 10 mg of atorvastatin, representing an absolute reduction in the rate of major cardiovascular events of 2.2 percent and a 22 percent relative reduction in risk (hazard ratio, 0.78; 95 percent confidence interval, 0.69 to 0.89; P&lt:0.001). There was no difference between the two treatment groups in overall mortality."

"CONCLUSIONS: Intensive lipid-lowering therapy with 80 mg of atorvastatin per day in patients with stable CHD provides significant clinical benefit beyond that afforded by treatment with 10 mg of atorvastatin per day. This occurred with a greater incidence of elevated aminotransferase levels."

Unfortunately, the statement "There was no difference between the two treatment groups in overall mortality." is incorrect. According to the full study (hidden behind a pay-wall) there were 26 more deaths in the 80mg/day group than in the 10mg/day group. That's not statistically significant, as the group sizes were ~5,000 each. However, the statement didn't mention statistical significance.

Therefore, the statement "Intensive lipid-lowering therapy with 80 mg of atorvastatin per day in patients with stable CHD provides significant clinical benefit beyond that afforded by treatment with 10 mg of atorvastatin per day." is also incorrect. Dying is worse than having major cardiovascular events (heart attacks & strokes), which are survivable.

Why is there a disparity between the publicly-viewable abstract, the full study and reality? From the full study:-

"Funding for the study was provided by Pfizer Inc., New York, New York. Dr. Shepherd has received consulting fees from AstraZeneca, GlaxoSmithKline, Merck, Oxford Biosensors, Pfizer Inc., and Schering-Plough, and lecture fees from AstraZeneca, Merck, and Schering-Plough. Dr. Kastelein has received consulting fees and lecture fees from Pfizer Inc., AstraZeneca, Merck, and Schering-Plough, and grant support from Pfizer Inc. and AstraZeneca. Dr. Bittner has received consulting fees from CV Therapeutics, Novartis, Pfizer Inc., Abbott, and Reliant, and grant support from Pfizer Inc., Atherogenics, Merck, Kos Pharmaceuticals, Abbott, CV Therapeutics, and the National Institutes of Health. Dr. Deedwania has received consulting fees and lecture fees from Pfizer Inc. and AstraZeneca. Dr. Breazna, Dr. Wilson, and Dr. Zuckerman are all employees of Pfizer Inc. Mr. Dobson is an employee of Envision Pharma Ltd., which was a paid consultant to Pfizer Inc. in connection with the development of the manuscript. Dr. Wenger has received consulting fees from CV Therapeutics, Sanofi-Aventis, Schering-Plough, AstraZeneca, Abbott, Merck, and Pfizer Inc., and grant support from Pfizer Inc., Merck, and the National Heart, Lung, and Blood Institute."

Atorvastatin is manufactured by Pfizer Inc.

Conflict of interest:

I like the article Is Vitamin D Shooting Me in the Foot?, because Dr. Ken D. Berry prescribes his patients an effective dose of Vitamin D3, even though it results in him losing money due to the drastic reduction in the number of benign skin cancers for him to freeze-off. Now, that's what I call integrity!

Can a breast cancer surgeon (who receives payment for curing breast cancer using surgery) give a truly impartial opinion on other cancer cures, or cancer prevention? Does he always clearly state his competing interest? I think not!