[R] Use of R in clinical trials

Dieter Menne dieter.menne at menne-biomed.de
Sat Feb 20 18:44:18 CET 2010

If you check


you will note that this thread has the largest number of read since years.
Looks like an encouragement to Mark to keep the mentioned CRAN document

To add a more serious note to my sarcastic comments earlier:

I don't think the FDA or our national agencies in Europe are to blame. I
know that they have eminent statisticians there who know what they are
talking of and are much more flexible than the culprits.

The people to blame for the "Nobody got fired for using SAS" attitude are
reviewers and bosses with mainly medical background who make decisions. It
the difference in the use of the term "validated" which leads to confusion.

A method is considered "validated" in medicine when it has been compared
with a gold standard and is non-inferior within reasonable limits. For
example, in the diagnosis of a gastric ulcer gastroscopy is the gold
standard, and cheaper or less invasive tests are measured against that. 

However, sometimes gold standards are the easy way out to avoid litigation,
and statistical evidence against these is brushed aside. Think of year it
needed to accept the Australian bush doctor's evidence that the bacteria
Helicobactor pylori is a main determinant for gastric ulcers; everyone
"knew" that ulcers were caused by stress alone.

Or gastric emptying: the "gold standard" is (was?) the use of a radioactive
marker that was recorded after a meal. Since radioactivity cannot rise out
of nothing, it was a well known fact that stomach content always goes down
after a meal. After people started measuring the real volume of the liquid
in the stomach with MRI imaging, it came out that the content INCREASED
after the meal due to strong gastric secretion. Despite visible evidence
from the images, the increase was considered "not validated", because is was
in contradiction of the gold standard.

"Validated" in medicine means: Some well-known person has made a publication
on the subject. He or she may be right, but not always.

Mention the word three times in a discussion, and my blood pressure is at
200 mmHg

My message: If you hear "not validated"  or "validated", question it. 


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