Between-trial heterogeneity in meta-analyses may be partially explained by reported design characteristics

Kirsty M Rhodes, Rebecca M Turner, Jelena Savović, Hayley Jones, David Mawdsley, Julian Higgins

Research output: Contribution to journalArticle (Academic Journal)

8 Citations (Scopus)
285 Downloads (Pure)

Abstract

Objective
We investigated the associations between risk of bias judgments from Cochrane reviews for sequence generation, allocation concealment and blinding and between-trial heterogeneity.

Study Design and Setting
Bayesian hierarchical models were fitted to binary data from 117 meta-analyses, to estimate the ratio λ by which heterogeneity changes for trials at high/unclear risk of bias, compared to trials at low risk of bias. We estimated the proportion of between-trial heterogeneity in each meta-analysis that could be explained by the bias associated with specific design characteristics.

Results
Univariable analyses showed that heterogeneity variances were, on average, increased among trials at high/unclear risk of bias for sequence generation (Math Eq 1.14, 95% interval: 0.57 to 2.30) and blinding (Math Eq 1.74, 95% interval: 0.85 to 3.47). Trials at high/unclear risk of bias for allocation concealment were on average less heterogeneous (Math Eq 0.75, 95% interval: 0.35 to 1.61). Multivariable analyses showed that a median of 37% (95% interval: 0% to 71%) heterogeneity variance could be explained by trials at high/unclear risk of bias for sequence generation, allocation concealment and/or blinding. All 95% intervals for changes in heterogeneity were wide and included the null of no difference.

Conclusion
Our interpretation of the results is limited by imprecise estimates. There is some indication that between-trial heterogeneity could be partially explained by reported design characteristics, and hence adjustment for bias could potentially improve accuracy of meta-analysis results.
Original languageEnglish
Pages (from-to)45-54
Number of pages10
JournalJournal of Clinical Epidemiology
Volume95
Early online date5 Dec 2017
DOIs
Publication statusPublished - Mar 2018

Keywords

  • Meta-analysis
  • Heterogeneity
  • Sequence generation
  • Allocation concealment
  • Blinding
  • Randomized trials

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