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Majority who take anti-depressants not represented in clinical trials

Thursday, April 30th, 2009

A new study suggests that the majority of people taking anti-depressants would be screened out of clinical trials for these drugs. Researchers found that this creates a difference in how effective a drug is in trial versus practice.


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In order to avoid tainting the results of a clinical trial, people with other physical or mental health issues are typically excluded. So are people with milder forms of depression because they might be more likely to experience a placebo effect.

University of Pittsburgh researchers found that of about 3,000 people taking the common anti-depressant Citalopram, only 22 percent could have participated in the clinical trial for this drug. Lead Researcher Dr. Stephen Wisniewski says this could explain why physicians find that the drug works less well in practice than in the trials:

Wisniewski: They have to realize that the outcomes they may expect to see they might not see because the person they are treating is most likely not like the people that were included in the trial

Dr. Jerrold Rosenbaum of Massachusetts General Hospital says clinical trials are limited in how much information they can provide – but they work as a guideline for physicians:

Rosenbaum: So the practice of medicine relies on the fact that the physician is trained and informed and will use that information in creating a best practice for an individual patient.

This research was part of a large national study of the treatment of depression.

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