Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions

Abstract Background Recent methodologic evidence suggests that lack of blinding in randomized trials can result in under- or overestimation of the treatment effect size. The objective of this study is to quantify the extent of bias associated with blinding in randomized controlled trials of oral hea...

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Main Authors: Humam Saltaji, Susan Armijo-Olivo, Greta G. Cummings, Maryam Amin, Bruno R. da Costa, Carlos Flores-Mir
Format: Article
Language:English
Published: BMC 2018-05-01
Series:BMC Medical Research Methodology
Subjects:
Online Access:http://link.springer.com/article/10.1186/s12874-018-0491-0
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spelling doaj-fbd5e99ec7cd4cb2ae0043710562414e2020-11-24T20:40:20ZengBMCBMC Medical Research Methodology1471-22882018-05-0118111810.1186/s12874-018-0491-0Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventionsHumam Saltaji0Susan Armijo-Olivo1Greta G. Cummings2Maryam Amin3Bruno R. da Costa4Carlos Flores-Mir5Orthodontic Graduate Program, School of Dentistry, Edmonton Clinic Health Academy, University of AlbertaFaculty of Rehabilitation Medicine, University of AlbertaFaculty of Nursing, University of AlbertaDivision of Pediatric Dentistry, School of Dentistry, University of AlbertaDepartment of Physical Therapy, Institute of Primary Health Care (BIHAM), Florida International UniversityDivision of Orthodontics, School of Dentistry, University of AlbertaAbstract Background Recent methodologic evidence suggests that lack of blinding in randomized trials can result in under- or overestimation of the treatment effect size. The objective of this study is to quantify the extent of bias associated with blinding in randomized controlled trials of oral health interventions. Methods We selected all oral health meta-analyses that included a minimum of five randomized controlled trials. We extracted data, in duplicate, related to nine blinding-related criteria, namely: patient blinding, assessor blinding, care-provider blinding, investigator blinding, statistician blinding, blinding of both patients and assessors, study described as “double blind”, blinding of patients, assessors, and care providers concurrently, and the appropriateness of blinding. We quantified the impact of bias associated with blinding on the magnitude of effect size using a two-level meta-meta-analytic approach with a random effects model to allow for intra- and inter-meta-analysis heterogeneity. Results We identified 540 randomized controlled trials, included in 64 meta-analyses, analyzing data from 137,957 patients. We identified significantly larger treatment effect size estimates in trials that had inadequate patient blinding (difference in treatment effect size = 0.12; 95% CI: 0.00 to 0.23), lack of blinding of both patients and assessors (difference = 0.19; 95% CI: 0.06 to 0.32), and lack of blinding of patients, assessors, and care-providers concurrently (difference = 0.14; 95% CI: 0.03 to 0.25). In contrast, assessor blinding (difference = 0.06; 95% CI: -0.06 to 0.18), caregiver blinding (difference = 0.02; 95% CI: -0.04 to 0.09), principal-investigator blinding (difference = − 0.02; 95% CI: -0.10 to 0.06), describing a trial as “double-blind” (difference = 0.09; 95% CI: -0.05 to 0.22), and lack of an appropriate method of blinding (difference = 0.06; 95% CI: -0.06 to 0.18) were not associated with over- or underestimated treatment effect size. Conclusions We found significant differences in treatment effect size estimates between oral health trials based on lack of patient and assessor blinding. Treatment effect size estimates were 0.19 and 0.14 larger in trials with lack of blinding of both patients and assessors and blinding of patients, assessors, and care-providers concurrently. No significant differences were identified in other blinding criteria. Investigators of oral health systematic reviews should perform sensitivity analyses based on the adequacy of blinding in included trials.http://link.springer.com/article/10.1186/s12874-018-0491-0Randomized controlled trialMeta-analysisResearch methodologyStudy qualityBias
collection DOAJ
language English
format Article
sources DOAJ
author Humam Saltaji
Susan Armijo-Olivo
Greta G. Cummings
Maryam Amin
Bruno R. da Costa
Carlos Flores-Mir
spellingShingle Humam Saltaji
Susan Armijo-Olivo
Greta G. Cummings
Maryam Amin
Bruno R. da Costa
Carlos Flores-Mir
Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
BMC Medical Research Methodology
Randomized controlled trial
Meta-analysis
Research methodology
Study quality
Bias
author_facet Humam Saltaji
Susan Armijo-Olivo
Greta G. Cummings
Maryam Amin
Bruno R. da Costa
Carlos Flores-Mir
author_sort Humam Saltaji
title Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
title_short Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
title_full Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
title_fullStr Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
title_full_unstemmed Influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
title_sort influence of blinding on treatment effect size estimate in randomized controlled trials of oral health interventions
publisher BMC
series BMC Medical Research Methodology
issn 1471-2288
publishDate 2018-05-01
description Abstract Background Recent methodologic evidence suggests that lack of blinding in randomized trials can result in under- or overestimation of the treatment effect size. The objective of this study is to quantify the extent of bias associated with blinding in randomized controlled trials of oral health interventions. Methods We selected all oral health meta-analyses that included a minimum of five randomized controlled trials. We extracted data, in duplicate, related to nine blinding-related criteria, namely: patient blinding, assessor blinding, care-provider blinding, investigator blinding, statistician blinding, blinding of both patients and assessors, study described as “double blind”, blinding of patients, assessors, and care providers concurrently, and the appropriateness of blinding. We quantified the impact of bias associated with blinding on the magnitude of effect size using a two-level meta-meta-analytic approach with a random effects model to allow for intra- and inter-meta-analysis heterogeneity. Results We identified 540 randomized controlled trials, included in 64 meta-analyses, analyzing data from 137,957 patients. We identified significantly larger treatment effect size estimates in trials that had inadequate patient blinding (difference in treatment effect size = 0.12; 95% CI: 0.00 to 0.23), lack of blinding of both patients and assessors (difference = 0.19; 95% CI: 0.06 to 0.32), and lack of blinding of patients, assessors, and care-providers concurrently (difference = 0.14; 95% CI: 0.03 to 0.25). In contrast, assessor blinding (difference = 0.06; 95% CI: -0.06 to 0.18), caregiver blinding (difference = 0.02; 95% CI: -0.04 to 0.09), principal-investigator blinding (difference = − 0.02; 95% CI: -0.10 to 0.06), describing a trial as “double-blind” (difference = 0.09; 95% CI: -0.05 to 0.22), and lack of an appropriate method of blinding (difference = 0.06; 95% CI: -0.06 to 0.18) were not associated with over- or underestimated treatment effect size. Conclusions We found significant differences in treatment effect size estimates between oral health trials based on lack of patient and assessor blinding. Treatment effect size estimates were 0.19 and 0.14 larger in trials with lack of blinding of both patients and assessors and blinding of patients, assessors, and care-providers concurrently. No significant differences were identified in other blinding criteria. Investigators of oral health systematic reviews should perform sensitivity analyses based on the adequacy of blinding in included trials.
topic Randomized controlled trial
Meta-analysis
Research methodology
Study quality
Bias
url http://link.springer.com/article/10.1186/s12874-018-0491-0
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