Map of life expectancy at birth from Global Education Project.

Friday, October 13, 2006

Another open door crashed through . . .

But sometimes it pays to point out the obvious. There are intellectually respectable objections to the gold-standard Randomized Controlled Trial (RCT) as the only kind of evidence one ought to accept for choosing health-related interventions (see, for example, Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials, by Gordon Smith and Jill Pell.) Nevertheless, if a new drug can't show its superiority to alternatives which are cheaper and/or known to be safe in an RCT, there isn't likely to be much justification for using it.

As everybody who wasn't born yesterday ought to know, drug companies sponsor most of the clinical trials on which drug approvals are based, and guess what, there are lots of ways to rig those trials to make their drugs look good and guess what, they do it. One strategy to combat use of slanted trials, and cherry picking of favorable ones, in order to sell drugs, is called the systematic review. Ideally, authors of such reviews first try to find all of the studies on a subject such as a specific drug; then they evaluate them for quality according to specified criteria; then they add up the results of the good ones ("meta-analysis") to come up with a better estimate of the effectiveness of the drug than any single trial can produce.

The Cochrane Collaboration is a non-profit organization which for many years has been compiling a database of such systematic reviews done according to its exacting standards. However, reviews are also regularly published in journals. Some of these reviews are sponsored by, guess who? Yup, drug companies actually pay for reviews of trials of their own products, many of which trials of course they themselves paid for. So, some Danish guys did a Review of Reviews (yeah, I know, next we'll need a review of reviews of reviews) and I'll bet you'll never guess what they found out?

When there was a Cochrane review and an industry-funded review of the same drug within two years, the industry-funded review always recommended use of the drug without reservation; the Cochrane review never did. The industry-funded reviews were of much lower quality and often incorporated studies which had serious deficiencies. Conclusions? "Industry supported reviews of drugs should be read with caution as they were less transparent, had few reservations about methodological limitations of the included trials, and had more favourable conclusions than the corresponding Cochrane reviews." Well duhhh.

Now what should we do about the good doctors who get paid to write drug industry propaganda and publish it in medical journals?


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