Risk of bias over time in updates of Cochrane oral health reviews
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BORIS DOI
Publisher DOI
PubMed ID
30342067
Description
OBJECTIVES
To assess the changes in the risk of bias (RoB) across different versions of the same Cochrane systematic review, and to identify characteristics of systematic reviews which may be associated with different RoB scores by means of regression analysis.
METHODS
We examined changes in RoB ratings in domains of randomized controlled trials (RCTs) and controlled trials (CTs) included in original Cochrane systematic reviews and their updates published in oral health. First, we checked the number of domains assessed for RoB in the different versions of the systematic review. Then, we computed the percentage of different ratings of RoB (low, high and unclear) in these systematic review versions. All data selection, extraction and analysis were conducted independently and in duplicate by two assessors. Time trends were reported in the form of line graphs. We also assessed systematic review characteristics as predictors of RoB scores by means of regression analysis.
RESULTS
A total of 173 reviews consisting of the original reviews and their updates were examined. The proportion of different ratings of RoB was kept stable over the different versions. However, in more recent versions, the proportion of unclear RoB slightly increased, and the proportion of high RoB decreased. Cochrane risk of bias domains were a significant RoB score predictor (Likelihood ratio test p-value < 0.001).
CONCLUSIONS
Methodological improvements in RCTs and CTs included in Cochrane reviews are needed. This comprehensive information on the RoB trend may help oral health researchers improving the methodology related to specific domains.
CLINICAL SIGNIFICANCE
Methodological improvements are necessary for primary studies included in Cochrane reviews in oral health. The increase of domains rated as unclear RoB is of concern and suggests that strategies should be developed to improve the level of communication between trialists and systematic reviewers.
To assess the changes in the risk of bias (RoB) across different versions of the same Cochrane systematic review, and to identify characteristics of systematic reviews which may be associated with different RoB scores by means of regression analysis.
METHODS
We examined changes in RoB ratings in domains of randomized controlled trials (RCTs) and controlled trials (CTs) included in original Cochrane systematic reviews and their updates published in oral health. First, we checked the number of domains assessed for RoB in the different versions of the systematic review. Then, we computed the percentage of different ratings of RoB (low, high and unclear) in these systematic review versions. All data selection, extraction and analysis were conducted independently and in duplicate by two assessors. Time trends were reported in the form of line graphs. We also assessed systematic review characteristics as predictors of RoB scores by means of regression analysis.
RESULTS
A total of 173 reviews consisting of the original reviews and their updates were examined. The proportion of different ratings of RoB was kept stable over the different versions. However, in more recent versions, the proportion of unclear RoB slightly increased, and the proportion of high RoB decreased. Cochrane risk of bias domains were a significant RoB score predictor (Likelihood ratio test p-value < 0.001).
CONCLUSIONS
Methodological improvements in RCTs and CTs included in Cochrane reviews are needed. This comprehensive information on the RoB trend may help oral health researchers improving the methodology related to specific domains.
CLINICAL SIGNIFICANCE
Methodological improvements are necessary for primary studies included in Cochrane reviews in oral health. The increase of domains rated as unclear RoB is of concern and suggests that strategies should be developed to improve the level of communication between trialists and systematic reviewers.
Date of Publication
2019-01
Publication Type
Article
Subject(s)
Keyword(s)
Bias Cochrane tool Methodological study Methods Randomized controlled trial Systematic reviews
Language(s)
en
Contributor(s)
Faggion, Clovis Mariano | |
Aranda, Luisiana | |
Alarcón, Marco Antonio | |
Diaz, Karla Tatiana |
Additional Credits
Series
Journal of dentistry
Publisher
Elsevier Science
ISSN
0300-5712
Access(Rights)
restricted