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Publication - Dr Jelena Savovic

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

    Citation

    Rhodes, KM, Turner, RM, Savović, J, Jones, H, Mawdsley, D & Higgins, J, 2018, ‘Between-trial heterogeneity in meta-analyses may be partially explained by reported design characteristics’. Journal of Clinical Epidemiology, vol 95., pp. 45-54

    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.

    Full details in the University publications repository