Abstract
BackgroundBlinding is a measure in randomized controlled trials (RCT) to reduce detection and performance bias. There is evidence that lack of blinding leads to overestimated treatment effects. Because of the physical component of interventions, blinding is not easily applicable in surgical trials. This is a protocol for a systematic review and empirical study about actual impact on outcomes and future potential of blinding in general and abdominal surgery RCT.Methods/designA systematic literature search in CENTRAL, MEDLINE and Web of Science will be conducted to locate RCT between 1996 and 2015 with a surgical intervention. General study characteristics and information on blinding methods will be extracted. The risk of performance and detection bias will be rated as low, unclear or high according to the Cochrane Collaboration’s tool for assessing risk of bias. The main outcome of interest will be the association of a high risk of performance or detection bias with significant trial results and will be tested at a level of significance of 5 %. Further, trials will be meta-analysed in a Mantel-Haenszel model comparing trials with high risk of bias to other trials at a level of significance of 5 %.DiscussionDetection and performance bias distort treatment effects. The degree of such bias in general and abdominal surgery is unknown. Evidence on influence of missing blinding would improve critical appraisal and conduct of general and abdominal surgery RCT.Systematic review registrationPROSPERO 2015:CRD42015026837.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-016-0226-4) contains supplementary material, which is available to authorized users.
Highlights
Blinding is a measure in randomized controlled trials (RCT) to reduce detection and performance bias
Research question This study aims to determine the status, potential and influence of blinding on outcomes in general and abdominal surgery RCT
A sensitivity analysis of the main outcome will be performed excluding all trials with an objective primary. This protocol describes the methods of a systematic review and empirical analysis, which will provide the present status and potential and influence of blinding on outcomes in general and abdominal surgery RCT
Summary
Blinding is a measure in randomized controlled trials (RCT) to reduce detection and performance bias. Because of the physical component of interventions, blinding is not applicable in surgical trials This is a protocol for a systematic review and empirical study about actual impact on outcomes and future potential of blinding in general and abdominal surgery RCT. The best external evidence is data from proper conducted randomized controlled trials (RCT) [2]. The Cochrane Collaboration defined the following standard domains of bias: random sequence generation, allocation sequence concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective outcome reporting and others. These domains are part of critical appraisal in order to judge validity of trials. The CONSORT statement (Consolidated Standards of Reporting Trials), a guideline on reporting of outcomes in randomized controlled trials, declared
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