BACKGROUND AND OBJECTIVE: To determine methods to assess the success of blinding in randomized controlled trials (RCTs). METHODS: We searched MEDLINE, the Cochrane Controlled Trials Register, and the Cochrane Method Register and performed a manual search to target studies that attempt to assess blinding and describe the methods used in those studies. RESULTS: A total of 90 reports were selected. Reports assessed the success of blinding participants (n = 58), care providers (n = 36), and outcome assessors (n = 15). Of the 58 reports assessing the success of blinding participants, 54 (93%) reported asking participants to guess their treatment assignment. There was no consistency in timing of assessment (e.g., once at the end of the trial, 57%, or several times during the trial, 26%) or modalities of answering (e.g., "do not know" answers, 43%, or participants forced to guess, 31%). A statistical analysis was performed in 57% of reports. The statistical analysis mainly compared the proportion of correct guesses to those produced by chance (32%) or checked for a relation between participants' guesses and treatment assignment (23%). CONCLUSIONS: Methods of assessing the success of blinding, analysis and reporting the results were inconsistent and questionable.
BACKGROUND AND OBJECTIVE: To determine methods to assess the success of blinding in randomized controlled trials (RCTs). METHODS: We searched MEDLINE, the Cochrane Controlled Trials Register, and the Cochrane Method Register and performed a manual search to target studies that attempt to assess blinding and describe the methods used in those studies. RESULTS: A total of 90 reports were selected. Reports assessed the success of blinding participants (n = 58), care providers (n = 36), and outcome assessors (n = 15). Of the 58 reports assessing the success of blinding participants, 54 (93%) reported asking participants to guess their treatment assignment. There was no consistency in timing of assessment (e.g., once at the end of the trial, 57%, or several times during the trial, 26%) or modalities of answering (e.g., "do not know" answers, 43%, or participants forced to guess, 31%). A statistical analysis was performed in 57% of reports. The statistical analysis mainly compared the proportion of correct guesses to those produced by chance (32%) or checked for a relation between participants' guesses and treatment assignment (23%). CONCLUSIONS: Methods of assessing the success of blinding, analysis and reporting the results were inconsistent and questionable.
Authors: Bruno T Saragiotto; Gustavo C Machado; Manuela L Ferreira; Marina B Pinheiro; Christina Abdel Shaheed; Christopher G Maher Journal: Cochrane Database Syst Rev Date: 2016-06-07
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