Abstract
ObjectiveTo quantify bias related to specific methodological characteristics in child-relevant randomized controlled trials (RCTs).DesignMeta-epidemiological study.Data SourcesWe identified systematic reviews containing a meta-analysis with 10–40 RCTs that were relevant to child health in the Cochrane Database of Systematic Reviews.Data ExtractionTwo reviewers independently assessed RCTs using items in the Cochrane Risk of Bias tool and other study factors. We used meta-epidemiological methods to assess for differences in effect estimates between studies classified as high/unclear vs. low risk of bias.ResultsWe included 287 RCTs from 17 meta-analyses. The proportion of studies at high/unclear risk of bias was: 79% sequence generation, 83% allocation concealment, 67% blinding of participants, 47% blinding of outcome assessment, 49% incomplete outcome data, 32% selective outcome reporting, 44% other sources of bias, 97% overall risk of bias, 56% funding, 35% baseline imbalance, 13% blocked randomization in unblinded trials, and 1% early stopping for benefit. We found no significant differences in effect estimates for studies that were high/unclear vs. low risk of bias for any of the risk of bias domains, overall risk of bias, or other study factors.ConclusionsWe found no differences in effect estimates between studies based on risk of bias. A potential explanation is the number of trials included, in particular the small number of studies with low risk of bias. Until further evidence is available, reviewers should not exclude RCTs from systematic reviews and meta-analyses based solely on risk of bias particularly in the area of child health.
Highlights
While randomized controlled trials (RCTs) are considered to be the gold standard for evidence on therapeutic interventions, [1] they are susceptible to bias. [2] Bias, or the systematic over- or under-estimation of a treatment’s effect, has important implications for decision-making
We found no significant differences in effect estimates for studies that were high/unclear vs. low risk of bias for any of the risk of bias domains, overall risk of bias, or other study factors
We found no differences in effect estimates between studies based on risk of bias
Summary
While randomized controlled trials (RCTs) are considered to be the gold standard for evidence on therapeutic interventions, [1] they are susceptible to bias. [2] Bias, or the systematic over- or under-estimation of a treatment’s effect, has important implications for decision-making. There is a growing body of empirical evidence based on metaepidemiological methods to quantify different biases in RCTs; there are some inconsistencies across studies and clinical areas. [4,5] Balk et al found variation in the direction of effects across studies which ‘‘calls into question whether any of these associations could provide a general rule for evaluating RCTs across clinical areas.’’ [4] the evidence to date has stemmed primarily from examination of trials involving adult participants; no metaepidemiological studies have focused on pediatric trials. [6,7] A meta-epidemiological study to quantify bias in a sample of pediatric trials would better inform the design, conduct, reporting, and interpretation of research in child health Research in children presents specific methodological and practical challenges, such as generating adequate sample sizes, and use of surrogate outcomes or outcome tools that have not been validated for the pediatric population. [6,7] A meta-epidemiological study to quantify bias in a sample of pediatric trials would better inform the design, conduct, reporting, and interpretation of research in child health
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