Posted by linkadge on September 11, 2007, at 18:16:47
In reply to Re: News - Antidepressants Vindicated?, posted by jhj on September 11, 2007, at 8:08:39
Untill very recently, drug companies did not need to disclose the trial results on many drugs. They can just keep testing and retesting a drug untill it happens to outperform placebo.
Prime Example:
Go to the GSK clinical trial registry for lamotrigine.
http://ctr.gsk.co.uk/Summary/lamotrigine/studylist.asp
You'd expect that since the drug is FDA approved for bipolar disorder that it outperform placebo right? Wrong. There are like 30 trials resitered there, for things ranging from unipolar depression, bipolar disorder to schizohprenia. Sure there are one or two trials that show the drug is more effective than placebo, but the majority show no such effectiveness.
Also read an article at, about bias on a decent site.
http://www.mcmanweb.com/news.htm
GSK has chosen to be fully honest about disclosing clinical trial informaiton, including those from failed clinical trials, but other companies are not being so open as they know how it will affect public preceptions of drugs.
They likely have failed trials that they are not disclosing. And the FDA does not require that failed trials be used to calculate the overall effectivness of a drug.
Publication bias also affects the viewpoints of the public. Simply put, effective trials get the attention.
A quote from:
http://www.biomedcentral.com/1472-6963/7/64
"The prevailing view amongst psychiatrists is that antidepressant medication is of proven efficacy in reducing the severity and duration of major depression and should therefore be used as its first line of treatment [1]. However systematic reviews of randomised double blind placebo controlled trials of antidepressant medication indicate that differences in outcome between drug and placebo arms are often marginal, and may be exaggerated by selective publication or even deliberate misrepresentation"
A meta analysis of placebo effect in 19 clinical trials.
http://www.geocities.com/oppressionactivist/METAANALYSIS_OF_PLACEBO_htm.htm
Also from:http://www.vaccinationnews.com/DailyNews/June2002/CanPlacebo25.htm
In a soon to be published study, Dr. Arif Khan, a psychiatrist at the Northwest Clinical Research Center in Washington, analyzed the Food and Drug Administration's database of 52 clinical trials in depression, involving nine new antidepressants, conducted from 1985 to 2000. ***Since the agency requires drug companies to report all data from all studies for drugs under development, the database can give a more accurate picture of a new drug's efficacy than the medical journals***, where positive findings are far more likely to be reported than negative ones.
Dr. Khan found that in only 48 percent of the 52 clinical trials was the antidepressant superior to the placebo.
Linkadge
poster:linkadge
thread:781684
URL: http://www.dr-bob.org/babble/20070911/msgs/782296.html