Association of the study characteristics with estimates of effect size in studies of ecstasy use

EM Taylor, NM Greene, CJ Morgan, MR Munafo

Research output: Contribution to journalArticle (Academic Journal)

3 Citations (Scopus)

Abstract

Studies of the chronic effects of MDMA, or ‘ecstasy’, in humans have been largely inconsistent. We explored whether study-level characteristics are associated with the effect size estimate reported. We based our analyses on the recent systematic review by Rogers and colleagues, focusing on those meta-analyses within this report where there was a relatively large number of studies contributing to each individual meta-analysis. Linear regression was used to investigate the association between study level variables and effect size estimate, weighted by the inverse of the SE of the effect size estimate, with cluster correction for studies which contributed multiple estimates. This indicated an association between effect size estimate and both user group, with smaller estimates among studies recruiting former users compared with those recruiting current users, and control group, with smaller estimates among studies recruiting polydrug user controls compared with those recruiting drug-naı¨ve controls. In addition, increasing year of publication was associated with reduced effect size estimate, and there was a trend level association with prevalence of ecstasy use, reflecting smaller estimates among studies conducted in countries with higher prevalence of ecstasy use. Our data suggest a number of study-level characteristics which appear to influence individual study effect size estimates. These should be considered when designing future studies, and also when interpreting the ecstasy literature as a whole.
Translated title of the contributionAssociation of the study characteristics with estimates of effect size in studies of ecstasy use
Original languageEnglish
Pages (from-to)1573 - 1577
Number of pages5
JournalJournal of Psychopharmacology
Volume25
DOIs
Publication statusPublished - 2011

Structured keywords

  • Brain and Behaviour
  • Tobacco and Alcohol

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