Dataset Information

Why has the antidepressant-placebo difference in antidepressant clinical trials diminished over the past three decades?

ABSTRACT: The increasing rate of failure of antidepressant clinical trials has led to the assertion that antidepressants do not have meaningful clinical benefits. Our hypothesis was that the decrease in antidepressant-placebo differences in antidepressant clinical trials over the past three decades could be explained by changes in research design features rather than a lack of potency of the antidepressants being tested. We collected data from 130 double blind placebo controlled antidepressant clinical trials conducted between 1981 and 2008 that included 35,122 depressed patients with 23,157 patients assigned to antidepressants and 11,965 assigned to placebo. We conducted a hierarchical regression analysis of change in HAM-D scores in antidepressant and placebo groups separately with year of publication, and research design features as independent variables. We found that antidepressant-placebo differences in antidepressant clinical trials have declined markedly over the past three decades. Decline in change scores in the antidepressant group was related to mean total baseline HAM-D scores in the trial, the version of HAM-D used, and duration of trial. Similarly, decline in change scores in the placebo group was related to mean total baseline HAM-D scores, duration of trial, and year of publication. Overall, we found that antidepressant-placebo differences were statistically significantly higher in trials that used HAM-D 21 rather than HAM-D 17 and in trials that lasted 6 weeks or less. These data suggest that, apart from the efficacy of the antidepressant being tested, factors such as baseline HAM-D scores, version of HAM-D used and duration of trial have a significant impact on outcome. As such a clinician's assessment of the usefulness of antidepressants should not be based solely on the results of such clinical trials. In the meantime there is a need for continuing research to improve the methodology of antidepressant clinical trials. These data suggest that many aspects of the design of antidepressant trials have a significant impact on outcome. Further, these data suggest that the results of more recent placebo controlled trials do not adequately inform clinicians about the potential utility of antidepressants.

SUBMITTER: Khan A

PROVIDER: S-EPMC6493812 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Why has the antidepressant-placebo difference in antidepressant clinical trials diminished over the past three decades?

Khan Arif A Bhat Amritha A Kolts Russell R Thase Michael E ME Brown Walter W

CNS neuroscience & therapeutics 20100416 4

The increasing rate of failure of antidepressant clinical trials has led to the assertion that antidepressants do not have meaningful clinical benefits. Our hypothesis was that the decrease in antidepressant-placebo differences in antidepressant clinical trials over the past three decades could be explained by changes in research design features rather than a lack of potency of the antidepressants being tested. We collected data from 130 double blind placebo controlled antidepressant clinical tr ...[more]

PMID: 20406269

Similar Datasets

Project description:BACKGROUND:Patient expectancy of therapeutic improvement is a primary mediator of placebo effects in antidepressant clinical trials, but its mechanisms are poorly understood. This study employed a novel antidepressant trial design, with integrated functional magnetic resonance imaging (fMRI), to manipulate patient outcome expectancy and examine its neural mediators. METHOD:Twenty-three depressed outpatients, in a randomized controlled trial were assigned to either Open (high outcome expectancy) or Placebo-controlled (low outcome expectancy) treatment with citalopram for eight weeks. fMRI scans were acquired before and after the expectancy manipulation (before medication treatment), while participants performed a masked emotional face task. Focusing on an amygdala region-of-interest (ROI), we tested a model where reduction in amygdala activation mediated outcome expectancy effects on the slope of change in depressive symptoms. RESULTS:Following the manipulation, significant differences between conditions were found in neural activation changes in the amygdala, as well as in superior temporal gyrus, insula, and thalamus. Findings support the proposed mediation model according to which activation in the left amygdala ROI decreased significantly in the Open as opposed to the Placebo-controlled group following randomization (p?=?0.009) for sad vs. neutral face contrast. The reduced left amygdala activation, in turn, was a significant predictor of decreased depressive symptoms during the trial (p?=?0.007), and the mediation model was significant. CONCLUSIONS:Results from this study, the first designed to identify the neural mechanisms of expectancy augmentation in an antidepressant randomized control trial, suggest that therapeutic modulation of amygdala activity may be an important pathway by which patient outcome expectancy influences depressive symptoms. CLINICALTRIALS. GOV IDENTIFIER:NCT01919216; Trial name: Placebo Effects in the Treatment of Depression: Cognitive and Neural Mechanisms, URL: https://clinicaltrials.gov/ct2/show/NCT01919216.

Project description:AimThe prevalence and mortality of abdominal aortic aneurysms (AAA) has been reported to decline. The aim of this study is to compare survival, prevalence, and repair rate of AAA in Denmark in the 1990s, the 2000s and the 2010s - and to examine any change in factors known to influence the prevalence.MethodsBaseline status and up to 5-year outcomes of 34,079 general population men aged 65-74 were obtained from three RCTs; the Viborg study (1994-1998, n=4,860), the Viborg Vascular (VIVA) trial (2008-2011, n=18,748), and the Danish Cardiovascular (DANCAVAS) trial (2015-2018, n=10,471). After the millennium (VIVA and DANCAVAS) men with AAA were further offered low dose aspirin and statins. Follow-up data were not available for the DANCAVAS trial yet.ResultsAcross the three decades, the AAA prevalence was 3.8% (Reference), 3.3% (p<0.001) and 4.2% (p=0.882), the proportion of smokers were 62%, 42% and 34% (p<0.001) amongst men with AAA, but AAA risk associations with smoking increased during the decades suggesting increased tobacco consumption of smokers. In addition, the proportions of attenders with ischemic heart disease or stroke increased significantly. The aneurysmal progression rate in the 1990s was 2.90 vs 2.98 mm/year in the 2000s (p=0.91). The need for preventive AAA repair increased insignificantly in the 2000s (Age adj. HR= 1.29, 95% C.I.: 0.95; 1.71, p=0.10), and mortality of men with screen-detected AAA was lower in the 2000s compared to the 1990s (Age-adj. HR= 0.28, 95% C.I.: 0.22; 0.36, p<0.001).ConclusionThe Danish prevalence of AAA today compares to the nineties. Unchanged aneurysmal progression rates combined with improved survival of men at risk of AAA leave them in longer time to develop an AAA, be diagnosed and to need later aneurysmal repair or experience rupture.Clinical trial registrationsViborg study: No possibility of registration in the nineties. VIVA: NCT00662480, URL: https://clinicaltrials.gov/show/NCT00662480, DANCAVAS: ISRCTN12157806, URL: http://www.isrctn.com/ISRCTN12157806.

Project description:ImportancePragmatic trials test interventions using designs that produce results that may be more applicable to the population in which the intervention will be eventually applied.ObjectiveTo investigate how pragmatic or explanatory cardiovascular (CV) randomized clinical trials (RCT) are, and if this has changed over time.Data sourceSix major medical and CV journals, including New England Journal of Medicine, Lancet, JAMA, Circulation, European Heart Journal, and Journal of the American College of Cardiology.Study selectionAll CV-related RCTs published during 2000, 2005, 2010, and 2015 were identified and included.Data extraction and synthesisIncluded RCTs were assessed by 2 independent adjudicators with expertise in RCT and CV medicine.Main outcomes and measuresThe outcome measure was the level of pragmatism evaluated using the Pragmatic Explanatory Continuum Index Summary (PRECIS)-2 tool, which uses a 5-point ordinal scale (ranging from very pragmatic to very explanatory) across 9 domains of trial design, including eligibility, recruitment, setting, organization, intervention delivery, intervention adherence, follow-up, primary outcome, and analysis.ResultsOf 616 RCTs, the mean (SD) PRECIS-2 score was 3.26 (0.70). The level of pragmatism increased over time from a mean (SD) score of 3.07 (0.74) in 2000 to 3.46 (0.67) in 2015 (P < .001 for trend; Cohen d relative effect size, 0.56). The increase occurred mainly in the domains of eligibility, setting, intervention delivery, and primary end point. PRECIS-2 score was higher for neutral trials than those with positive results (P < .001) and in phase III/IV trials compared with phase I/II trials (P < .001) but similar between different sources of funding (public, industry, or both; P = .38). More pragmatic trials had more sites, larger sample sizes, longer follow-ups, and mortality as the primary end point.Conclusions and relevanceThe level of pragmatism increased moderately over 2 decades of CV trials. Understanding the domains of current and future clinical trials will aid in the design and delivery of CV trials with broader application.

Dataset Information

Why has the antidepressant-placebo difference in antidepressant clinical trials diminished over the past three decades?

Publications

Why has the antidepressant-placebo difference in antidepressant clinical trials diminished over the past three decades?

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets