Advances in the meta-analysis of heterogeneous clinical trials II: the quality effects model

Advances in the meta-analysis of heterogeneous clinical trials II: the quality effects model

This article examines the performance of the updated quality effects (QE) estimator formeta-analysis of heterogeneous studies. It is shown that this approach leads to a decreased mean squared error (MSE) of the estimator
while maintaining the nominal level of coverage probability of the confidence interval. Extensive simulation
studies confirm that this approach leads to the maintenance of the correct coverage probability of the confidence
interval, regardless of the level of heterogeneity, as well as a lower observed variance compared to the random effects
(RE) model. The QE model is robust to subjectivity in quality assessment down to completely random entry,
in which case its MSE equals that of the RE estimator.When the proposed QEmethod is applied to ameta-analysis
of magnesium for myocardial infarction data, the pooled mortality odds ratio (OR) becomes 0.81 (95% CI 0.61–
1.08) which favors the larger studies but also reflects the increased uncertainty around the pooled estimate. In
comparison, under the RE model, the pooled mortality OR is 0.71 (95% CI 0.57–0.89) which is less conservative
than that of the QE results. The new estimation method has been implemented into the free meta-analysis software
MetaXL which allows comparison of alternative estimators and can be downloaded fromwww.epigear.com.

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