Information on blinding in registered records of clinical trials

Table 1 Trialists’ interpretations of the terms ‘single-blind’ and ‘double-blind’ ^a

Who was mentioned as blinded	Trial was labelled as
	Single-blind	Double-blind
Patient, caregiver, data analyst / investigator, outcomes assessor	0	79
Patient, caregiver, data analyst / investigator	0	19
Patient, caregiver, outcomes assessor	0	2
Patient, data analyst / investigator, outcomes assessor	0	9
Caregiver, data analyst / investigator, outcomes assessor	0	1
Data analyst / investigator, outcomes assessor	0	1
Patient, outcomes assessor	0	12
Patient, data analyst / investigator	1	68
Patient, caregiver	0	3
Outcomes assessor	22	0
Data analyst / investigator	16	0
Caregiver	1	0
Patient	26	0
Total	66	194

^aRecords that contained both blinding labels and information on who was blinded mainly originated from two registries. One registry asked for information on the blinding status of subjects, clinicians or therapists, outcome assessors and/or data analysts. The other registry asked for information on the blinding status of subjects, caregivers, outcome assessors and/or investigators. Because of the similarity between these two classifications, for this table, trials that were labeled to the fourth category of ‘data analysts’ on one registry and ‘investigators’ on the other were categorized as the same group.

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