Article type
Year
Abstract
Background: Blinding is a key issue in studies assessing the effectiveness of health care interventions, especially in a randomised controlled trial (RCT). The extent to which blinding influences the direction and magnitude of the effects of an intervention is influenced by the type of intervention, the study design and the type of outcome that will be assessed. The Cochrane Risk of Bias Tool for reviews of RCTs, has three categories of individuals must be considered in the blinding process: the participants, health personnel and the outcome assessors. This implies that authors have to report on the blinding process since it is not always possible to blind participants, health personnel and outcome assessors with regards to the intervention under study.
Objectives: To evaluate whether blinding of participants, personnel and outcome assessors is accurately reported in Cochrane Reviews of randomised controlled trials.
Methods: We searched the Cochrane library for all new or updated reviews of RCTs in issue 1 and 2 of 2013. Two authors independently read through the included reviews for information on assessment of blinding in included studies. We resolved discrepancies through discussions and by consulting the third author.
Results: There were a total of 158 new or updated reviews. One or more RCTs were included in 131 of the reviews. In 124 (94.7%) of the reviews the authors specified who was blinded in the included studies. However, 31% of reviews did not clearly report on blinding of the participants, personnel and outcome assessors. Terms like ‘double-blind’ or ‘investigators’were frequently used and it was not clear who exactly was blinded.
Conclusions: Some Cochrane authors do not correctly report on blinding in the included studies. It is important for authors to specify the different individuals blinded and state, where appropriate, if blinding of participants or study personnel was not possible.
Objectives: To evaluate whether blinding of participants, personnel and outcome assessors is accurately reported in Cochrane Reviews of randomised controlled trials.
Methods: We searched the Cochrane library for all new or updated reviews of RCTs in issue 1 and 2 of 2013. Two authors independently read through the included reviews for information on assessment of blinding in included studies. We resolved discrepancies through discussions and by consulting the third author.
Results: There were a total of 158 new or updated reviews. One or more RCTs were included in 131 of the reviews. In 124 (94.7%) of the reviews the authors specified who was blinded in the included studies. However, 31% of reviews did not clearly report on blinding of the participants, personnel and outcome assessors. Terms like ‘double-blind’ or ‘investigators’were frequently used and it was not clear who exactly was blinded.
Conclusions: Some Cochrane authors do not correctly report on blinding in the included studies. It is important for authors to specify the different individuals blinded and state, where appropriate, if blinding of participants or study personnel was not possible.