Heterogeneity in Cochrane and non-Cochrane meta-analyses in orthodontics.
- Koletsi D Clinic of Orthodontics and Paediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland and Private Practice in Athens, Greece. Electronic address: d.koletsi@gmail.com.
- Fleming PS Department of Orthodontics, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
- Michelaki I School of Dentistry, National and Kapodistrian University of Athens, Athens, Greece.
- Pandis N Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Switzerland and Private Practice in Corfu, Greece.
- 2018-05-09
Published in:
- Journal of dentistry. - 2018
Cochrane
Heterogeneity
I(2)
Meta-analysis
Orthodontic
Humans
Meta-Analysis as Topic
Orthodontics
Publications
Research Report
Systematic Reviews as Topic
English
OBJECTIVES
Heterogeneity describes the percentage of variability across the study effects that can be attributed to between-study differences in a meta-analysis. The aim of this project was to explore the magnitude of heterogeneity in Cochrane and non-Cochrane meta-analyses in orthodontic research and to identify possible associations between heterogeneity (I2) and a number of study characteristics including number of studies, type of outcome and type of analysis.
METHODS
The contents of five major orthodontic journals and the Cochrane Database of Systematic Reviews were electronically searched from January 2000 to December 2017 to identify Systematic Reviews (SRs) with at least one meta-analysis. Included records were screened for reporting of I2 classified into four categories: 0%, 1-29%, 30-59%, 60-100%. Associations between I2 and review-level and synthesis-level characteristics were tested. Univariable and multivariable mixed effects ordinal logistic regression was used to identify significant predictors for statistical heterogeneity.
RESULTS
A total of 72 SRs comprising 391 meta-analyses were included with the majority based on non-Cochrane reviews (n = 54, 75%). Overall, 125 meta-analyses (32%) reported heterogeneity explained by chance (I2 = 0%), whereas high values of I2 (∼60-100%) were seen in 152 syntheses (39%). In the multivariable analysis, inclusion of each additional study within the synthesis presented 20% higher odds for substantial/considerable heterogeneity compared to lower heterogeneity categories (OR = 1.20; 95%CIs: 1.09, 1.31; p < 0.001). Use of fixed effect analysis (OR = 0.25; 95%CIs: 0.12, 0.55; p = 0.001) was associated with significantly lower odds. Cochrane versus non-Cochrane meta-analyses were not associated with higher odds for substantial/considerable heterogeneity (OR = 2.81; 95%CIs: 0.53, 14.91; p = 0.22).
CONCLUSIONS
Substantial statistical heterogeneity is present within a considerable number of orthodontic meta-analyses. Further efforts should be made to improve understanding of decisions to undertake meta-analyses and selection of studies eligible for inclusion.
CLINICAL SIGNIFICANCE
The consistency of meta-analyses could be improved with more careful consideration of individual study characteristics. Reduced heterogeneity in meta-analyses will ensue more solid evidence based decisions for clinical practice.
Heterogeneity describes the percentage of variability across the study effects that can be attributed to between-study differences in a meta-analysis. The aim of this project was to explore the magnitude of heterogeneity in Cochrane and non-Cochrane meta-analyses in orthodontic research and to identify possible associations between heterogeneity (I2) and a number of study characteristics including number of studies, type of outcome and type of analysis.
METHODS
The contents of five major orthodontic journals and the Cochrane Database of Systematic Reviews were electronically searched from January 2000 to December 2017 to identify Systematic Reviews (SRs) with at least one meta-analysis. Included records were screened for reporting of I2 classified into four categories: 0%, 1-29%, 30-59%, 60-100%. Associations between I2 and review-level and synthesis-level characteristics were tested. Univariable and multivariable mixed effects ordinal logistic regression was used to identify significant predictors for statistical heterogeneity.
RESULTS
A total of 72 SRs comprising 391 meta-analyses were included with the majority based on non-Cochrane reviews (n = 54, 75%). Overall, 125 meta-analyses (32%) reported heterogeneity explained by chance (I2 = 0%), whereas high values of I2 (∼60-100%) were seen in 152 syntheses (39%). In the multivariable analysis, inclusion of each additional study within the synthesis presented 20% higher odds for substantial/considerable heterogeneity compared to lower heterogeneity categories (OR = 1.20; 95%CIs: 1.09, 1.31; p < 0.001). Use of fixed effect analysis (OR = 0.25; 95%CIs: 0.12, 0.55; p = 0.001) was associated with significantly lower odds. Cochrane versus non-Cochrane meta-analyses were not associated with higher odds for substantial/considerable heterogeneity (OR = 2.81; 95%CIs: 0.53, 14.91; p = 0.22).
CONCLUSIONS
Substantial statistical heterogeneity is present within a considerable number of orthodontic meta-analyses. Further efforts should be made to improve understanding of decisions to undertake meta-analyses and selection of studies eligible for inclusion.
CLINICAL SIGNIFICANCE
The consistency of meta-analyses could be improved with more careful consideration of individual study characteristics. Reduced heterogeneity in meta-analyses will ensue more solid evidence based decisions for clinical practice.
- Language
-
- English
- Open access status
- green
- Identifiers
-
- DOI 10.1016/j.jdent.2018.05.003
- PMID 29738788
- Persistent URL
- https://sonar.ch/global/documents/185168
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