Effect sizes in cumulative meta-analyses of mental health randomized trials evolved over time

Meta-analyses of randomized trials may incorporate new evidence, and estimated treatment effects change over time. We evaluated whether the certainty and estimates of efficacy and tolerability of mental health interventions change over time, as more trials appear on the same topics. One hundred meta...

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Bibliographic Details
Published in:Journal of clinical epidemiology 2004-11, Vol.57 (11), p.1124-1130
Main Authors: Trikalinos, Thomas A., Churchill, Rachel, Ferri, Marica, Leucht, Stefan, Tuunainen, Arja, Wahlbeck, Kristian, Ioannidis, John P.A.
Format: Article
Language:English
Subjects:
Bias
Biological and medical sciences
Data Interpretation, Statistical
Drug therapy
Effect size
Efficacy
Epidemiology
Failure
General aspects
Health promotion
Humans
Intervention
Medical sciences
Mental Disorders - therapy
Mental health
Meta-analysis
Meta-Analysis as Topic
Methodology
Public health. Hygiene
Public health. Hygiene-occupational medicine
Randomized Controlled Trials as Topic
Recursive cumulative meta-analysis
Statistical significance
Time Factors
Treatment Outcome
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Summary:Meta-analyses of randomized trials may incorporate new evidence, and estimated treatment effects change over time. We evaluated whether the certainty and estimates of efficacy and tolerability of mental health interventions change over time, as more trials appear on the same topics. One hundred meta-analyses (1,024 trial entries; 99,303 participants) with an outcome of death, relapse, failure or dropout and with five or more trials published in three or more different years were examined with cumulative meta-analysis and recursive cumulative meta-analysis. Eight meta-analyses reached formal statistical significance ( P < .05) at some point, but lost this significance eventually when more trials were published; typically large effect sizes in early trials were dissipated with further evidence. With 500 randomized subjects, 95% of the time, subsequent changes in odds ratio might be up to 1.5-fold. For death, relapse, and failure outcomes, a decrease in effect size was somewhat more common than an increase, when more data became available (157 vs. 125, P = .06). This was most clear for comparisons of pharmacotherapies versus placebo (79 vs. 51, P = .009). Evidence based on a small number of randomized subjects should be interpreted cautiously. Early treatment efficacy of pharmacotherapies is occasionally overestimated.
ISSN:0895-4356
1878-5921
DOI:10.1016/j.jclinepi.2004.02.018