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Does Study Design Influence Clinical Outcome?

Date:
July 5, 2009
Source:
Journal of Psychotherapy and Psychosomatics
Summary:
Response and remission rates to antidepressants are significantly affected by study type and duration. Clinicians and researchers must consider the study design when interpreting and designing RCTs of antidepressant medications, researchers urge.
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Clinicians and researchers synthesize data from randomized controlled trials (RCTs) of antidepressants to make conclusions about the efficacy of medications for depression. All treatments include nonspecific factors in addition to the specific effects of drugs, and study design may influence patient outcomes via nonspecific factors. This study investigated whether placebo control and treatment duration affect the outcome in antidepressant RCTs.

Medline and the Cochrane Database were searched to identify RCTs of antidepressants for major depression approved by the Food and Drug Administration. Included studies enrolled outpatient participants aged 18-65, lasted 6-12 weeks, compared an antidepressant to placebo or another antidepressant and were published in English after 1985. Excluded trials enrolled inpatients, pregnant women and subjects with psychosis or mania.

Mixed-effects logistic regression models including study type (placebo-controlled or comparator) and study duration (6, 8 or 12 weeks) as fixed effects determined whether these factors affected response and remission rates. In the 90 trials analyzed, the odds of depression response (OR = 1.79, 95% CI = 1.45-2.17, p < 0.001) and remission (OR 1.53, 95% CI = 1.11-2.11, p < 0.001) were significantly higher in comparator relative to placebo-controlled trials. Trials lasting 8 (OR = 1.37, CI = 1.14-1.64, p = 0.001) and 12 (OR = 1.52, CI = 1.12-2.07, p = 0.008) weeks had significantly greater response rates than 6-week trials without differing themselves.

Response and remission rates to antidepressants are significantly affected by study type and duration. Clinicians and researchers must consider the study design when interpreting and designing RCTs of antidepressant medications, researchers urge.


Story Source:

The above post is reprinted from materials provided by Journal of Psychotherapy and Psychosomatics. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rutherford et al. Does Study Design Influence Outcome? Psychotherapy and Psychosomatics, 2009; 78 (3): 172 DOI: 10.1159/000209348

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Journal of Psychotherapy and Psychosomatics. "Does Study Design Influence Clinical Outcome?." ScienceDaily. ScienceDaily, 5 July 2009. <www.sciencedaily.com/releases/2009/06/090622064703.htm>.
Journal of Psychotherapy and Psychosomatics. (2009, July 5). Does Study Design Influence Clinical Outcome?. ScienceDaily. Retrieved August 1, 2015 from www.sciencedaily.com/releases/2009/06/090622064703.htm
Journal of Psychotherapy and Psychosomatics. "Does Study Design Influence Clinical Outcome?." ScienceDaily. www.sciencedaily.com/releases/2009/06/090622064703.htm (accessed August 1, 2015).

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