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Highlights (what is new)
- •An analysis of 67,308 Cochrane meta-analyses suggests that unrestricted weighted least squares (UWLS) usually represent medical research better than random effects, often substantially so.
- •The better performance of UWLS is evident across meta-analyses regardless of heterogeneity, number of studies and type of outcome.
- •UWLS should be routinely reported in meta-analyses.
Abstract
Objective
To evaluate how well meta-analysis mean estimators represent reported medical research
and establish which meta-analysis method is better using widely accepted model selection
measures: Akaike information criterion (AIC) and Bayesian information criterion (BIC).
Study design and setting
We compiled 67,308 meta-analyses from the Cochrane Database of Systematic Reviews
(CDSR) published between 1997 and 2020, collectively encompassing nearly 600,000 medical
findings. We compared unrestricted weighted least squares (UWLS) versus random effects
(RE); fixed effect (FE) was also secondarily considered.
Results
The probability that a randomly selected systematic review from the CDSR would favor
UWLS over RE is 79.4% (CI95%: 79.1; 79.7). The odds ratio that a Cochrane systematic review would substantially
favor UWLS over RE is 9.33 (CI95%: 8.94; 9.73) using the conventional criterion that a difference in AIC (or BIC) of
two or larger represents a ‘substantial’ improvement. UWLS’s advantage over RE is
most prominent in the presence of low heterogeneity. However, UWLS also has a notable
advantage in high heterogeneity research, across different sizes of meta-analyses
and types of outcomes.
Conclusions
UWLS frequently dominates RE in medical research, often substantially. Thus, the unrestricted
weighted least squares should be reported routinely in the meta-analysis of clinical
trials.
Graphical abstract
Graphical Abstract
Keywords
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Article info
Publication history
Accepted:
March 1,
2023
Received in revised form:
February 16,
2023
Received:
December 16,
2022
Publication stage
In Press Journal Pre-ProofFootnotes
T. D. Stanley: Conceptualization; Formal analysis; Investigation; Methodology; Validation; Writing – original draft; Writing – review & editing.
John P. A. Ioannidis: Conceptualization; Writing – review & editing.
Maximilian Maier: Conceptualization; Writing –review & editing.
Hristos Doucouliagos: Conceptualization; Writing –review & editing.
Willem M. Otte: Software; Validation; Writing – review & editing.
František Bartoš: Conceptualization; Data curation; Formal analysis; Methodology; Validation; Software; Validation; Writing – review & editing.
Identification
Copyright
© 2023 Elsevier Inc. All rights reserved.
