Bias control in clinical trials: masking or blinding

Galvez-Olortegui, Jose; Gonzales-Saldaña, Jaime; Garcia-Gomez, Iván; Silva-Ocas, Isabel; Gutierrez-Arana, Jessica; Galvez-Olortegui, Tomás; Condor-Rojas, Yudy

doi:10.5867/medwave.2015.11.6349

Cited by 2 publications

(4 citation statements)

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“…The suggestion to establish explicit definitions for the term [ 7 , 18 ] is complicated by the fact that several groups or individuals can be blinded. Limiting “double-blind” to trials in which only 2 specific groups are blinded leaves other combinations without an equivalent term.…”

Section: Background: Problems With the Term “Double-blind”mentioning

confidence: 99%

“…That is, allocation concealment minimizes selection bias before participants have been assigned to experimental groups, whereas blinding minimizes surveillance, expectation, and ascertainment bias after group assignment. Many readers are not aware of this difference [ 2 , 5 , 6 , 8 , 12 , 13 , 15 , 18 – 20 ], perhaps because the terms “allocation” and “blinding” indicate neither the similarities nor the differences between the concepts.…”

Section: Background: Problems With the Term “Double-blind”mentioning

confidence: 99%

“…Some authors prefer “masking” to “blinding,” although the meaning of either term in a clinical trial may not be readily apparent to nonnative English speakers [ 18 , 22 ]. Further, some authors use the terms interchangeably [ 5 – 7 , 10 – 12 , 15 , 18 , 24 , 25 ], others insist that only masking be used [ 17 , 20 , 23 ], and still others insist that only blinding be used [ 2 , 5 , 22 ]. In addition, masking is sometimes used to describe how treatments are made indistinguishable [ 18 , 19 , 25 , 26 ], whereas blinding usually indicates which groups are unaware of treatment assignment [ 1 – 6 ].…”

Section: Background: Problems With the Term “Double-blind”mentioning

confidence: 99%

“…Further, some authors use the terms interchangeably [ 5 – 7 , 10 – 12 , 15 , 18 , 24 , 25 ], others insist that only masking be used [ 17 , 20 , 23 ], and still others insist that only blinding be used [ 2 , 5 , 22 ]. In addition, masking is sometimes used to describe how treatments are made indistinguishable [ 18 , 19 , 25 , 26 ], whereas blinding usually indicates which groups are unaware of treatment assignment [ 1 – 6 ]. Finally, searching the literature for “blinded,” “partially blind,” or “fully blind” randomized trials also identifies dozens of unwanted citations to the condition of being without sight.…”

Section: Background: Problems With the Term “Double-blind”mentioning

confidence: 99%

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

Lang

Stroup²

2020

Trials

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Background In randomized trials, the term “double-blind” (and its derivatives, single- and triple-blind, fully blind, and partially blind or masked) has no standard or widely accepted definition. Agreement about which groups are blinded is poor, and authors using these terms often do not identify which groups were blinded, despite specific reporting guidelines to the contrary. Nevertheless, many readers assume—incorrectly—that they know which groups are blinded. Thus, the term is ambiguous at best, misleading at worst, and, in either case, interferes with the accurate reporting, interpretation, and evaluation of randomized trials. The problems with the terms have been thoroughly documented in the literature, and many authors have recommended that they be abandoned. Proposal We and our co-signers suggest eliminating the use of adjectives that modify “blinding” in randomized trials; a trial would be described as either blinded or unblinded. We also propose that authors report in a standard table which groups or individuals were blinded, what they were blinded to, how blinding was implemented, and whether blinding was maintained. Individuals with dual responsibilities, such as caregiving and data collecting, would also be identified. If blinding was compromised, authors should describe the potential implications of the loss of blinding on interpreting the results. Conclusion “Double blind” and its derivatives are terms with little to recommend their continued use. Eliminating the use of adjectives that impart a false specificity to the term would reduce misinterpretations, and recommending that authors report who was blinded to what and how in a standard table would require them to be specific about which groups and individuals were blinded.

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Section: Background: Problems With the Term “Double-blind”mentioning

confidence: 99%