Wednesday, February 27, 2008

Prozac vs the Placebo or teh Spin vs Science?

Thus, the increased benefit for extremely depressed patients seems attributable to a decrease in responsiveness to placebo, rather than an increase in responsiveness to medication.

Today's Age reports (link via Blogocracy) that a recent study has found that most patients diagnosed with depression would get as much benefit from a daily sugar pill as they would from a dose of Prozac, Aropax or Effexor. You can access the original report here.

The report is helpfully provided in three versions - an abstract, an editor's summary, and the full report. In all three, the authors make their opinion that the reason anti-depressants appear to be clinically effective in cases of severe depression is because severe depressives are less responsive to placebos clear, in case anyone reading only one of the first two misses this very important point.
The relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication. (abstract)

The findings also show that the effect for these [severely depressed] patients seems to be due to decreased responsiveness to placebo, rather than increased responsiveness to medication. (editor's summary)

These statements are not particularly scientific - they're pure spin. What the authors are telling us, in plain English, is that anti-depressants do work better than placebos on severely depressed patients, but they would prefer to explain it away. It's not particularly rational - let's see what happens when we make a few substitutions:

Thus, the increased benefit of analgesics for patients with chronic severe pain seems attributable to a decrease in responsiveness to placebo, rather than an increase in responsiveness to medication.

The relationship between initial severity and analgesic efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication.

The findings also show that the effect for these patients [with chronic severe pain] seems to be due to decreased responsiveness to placebo, rather than increased responsiveness to medication.


Starts to look a little woolly-headed, doesn't it? More like the sort of thing that you would write if you had some deep-seated conviction that the use of analgesics to relieve pain was just plain wrong than an objective assessment of the evidence.

5 comments:

Lord Sedgwick said...

See you on Sunday?

Hope so.

The usual suspects will be here.

Anonymous said...

Last month, Slate published an article (Screw-ups over unpublished data or no, antidepressants still work) which demolished work based on this data.

Essentially, neither the patients nor the treatment protocols used in these studies were remotely representative of real world conditions.

Bwca said...
This comment has been removed by a blog administrator.
Anonymous said...

The article in Slate is by Peter Kramer of "Listening to Prozac" fame. The entire thesis of that book is that SSRIs transform personality in normal people in positive ways. If this is true, Dr Kramer's career is over. He is highly unlikely to agree.

This study looks right. What is called "extremely severe" depression now would have been mild to moderate 30 years ago. The medicalisation of human misery has been persistently pushed by the SSRI manufacturers for twenty years. Nice to see data push back.

Oh, and this isn't doctor bashing, prescribed various antidepressants a few times last week myself.

Gummo Trotsky said...

Interesting that the various reviews at Amazon don't exactly agree with your precis of the book's entire thesis as "... that SSRIs transform personality in normal people in positive ways." Also intersting that Amazon's review has this to say:

"Kramer has been criticized for seeming to advocate Prozac over psychotherapy or as a way of achieving personality changes not directly related to the disease of depression, such as improving one's social confidence or job performance. In fact, he makes no such recommendations; he was simply the first popular writer to suggest that these changes might occur. (He answers those critics in the afterword to this 1997 edition.)"

I might have to track down a real copy next week to see which is the more accurate summary of the book's "main thesis".