Record Status This is a bibliographic record of a published health technology assessment from a member of INAHTA. No evaluation of the quality of this assessment has been made for the HTA database. Citation Berkman ND, Santaguida PL, Viswanathan M, Morton SC. The empirical evidence of bias in trials measuring treatment differences. Rockville: Agency for Healthcare Research and Quality (AHRQ). Methods Research Report. 2014 Authors' objectives To comprehensively and systematically review and compare empirical evaluations of specific types of bias on effect estimates in randomized controlled trials (RCTs) reported in systematic reviews. Authors' conclusions Theory suggests that bias in the conduct of studies would influence treatment effects. Our review found some evidence of this effect in relation to some aspects of RCT study conduct. When the bias was present, commonly the treatment effect was increased, but rarely were the estimates precise in the individual studies. However, because this evidence is limited and uncertain with respect to the magnitude of the impact, this does not necessarily imply that systematic reviewers can eliminate assessment of risk of bias. Due to the complexity of evaluating precision in meta-epidemiological studies developed from potentially heterogeneous
meta-analyses or trials, we cannot be sure that studies were sufficiently powered. We suggest that systematic reviewers consider subgroup analyses, with and without studies with flaws in relation to specific biases of importance for review questions. Future studies evaluating the impact of biases on treatment effect should follow the lead of the BRANDO study and use modeling approaches that include careful construction of large datasets of trials (and eventually observational studies) designed to look at the effect of specific aspects of study conduct and the interrelationship between bias concerns. Indexing Status Subject indexing assigned by CRD MeSH Bias (Epidemiology); Clinical Trials as Topics Language Published English Country of organisation United States English summary An English language summary is available. Address for correspondence AHRQ, Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA Email: AHRQTAP@ahrq.hhs.gov AccessionNumber 32014001113 Date abstract record published 06/10/2014 |