Who knew? The misleading specificity of “double-blind” and what to do about it

Table 2 A standard table for reporting the use of blinding in randomized trials of pharmaceutical interventions

Group or individual blinded^a	Information withheld^b	Method of blinding^c,d	Blinding compromised
Required fields to be completed for all trials described as blinded
Person assigning participants to groups	Group assignment	Concealed allocation schedule	No
Participants	Group assignment	Placebo medications; sham surgeries	No
Care providers	Group assignment	Not told of group assignment	No
Data collectors and managers	Group assignment	Not told of group assignment	No
Outcome assessors	Purpose of study; group assignment; participant characteristics	Participants given numerical identifiers	No
Statisticians	Participant and group identities	Participants and groups given numerical identifiers	No
Supplemental fields for all blinded groups or individuals not mentioned above
Trial manager	Not applicable	. . .	. . .
Pharmacists	Not applicable	. . .	. . .
Laboratory technicians	Participant identities	Participants given numerical identifiers
Outcome adjudicators	Group assignment	Groups given numerical identifiers	Yes [put details in text]
Data monitoring and safety committees	Not applicable	. . .	. . .
Manuscript writers	Not blinded	. . .	. . .

^aOther groups or individuals in a trial that were capable of being blinded should be listed in the table, and whether or not they were blinded in the study should be indicated. Individuals with dual responsibilities, such as caregiving and data collecting, should be identified by combining the entries in the same row heading
^bAlthough group assignment is the information most commonly withheld in a blinded trial, data assessors, such as pathologists and radiologists, are often blinded to the purpose of the trial, group assignment, and the demographic and clinical characteristics of participants whose biopsy samples or images they are interpreting
^cIn many cases, authors should determine before the trial begins whether the method of blinding had a reasonable chance of being effective, including establishing the similarity between active and placebo preparations and the bioequivalent availability for two or more active drugs [33]. Testing the effectiveness of blinding after the trial has ended is uninformative because the results cannot be separated from pre-trial expectations of the success of the intervention [32]
^dIf blinding has been compromised, authors should report the fact and indicate the potential implications the loss of blinding might have for interpreting the results

ISSN: 1745-6215