Article

OBJECTIVES: (1) To develop trial protocols which promote the achievement of blind
outcome assessment. (2) To report outcome assessor beliefs regarding group
allocation at follow-up assessments. (3) To document and describe instances of
unblinding occurring during the trial to assist and inform rehabilitation
researchers and clinicians. DESIGN: Prospective longitudinal observational study.
An NHS Hospital Trust specializing in orthopaedic surgery. SUBJECTS: One
hundred and seven patients participating in a prospective pragmatic randomized
controlled trial investigating physiotherapy rehabilitation following total knee
arthroplasty, plus three outcome assessors. INTERVENTIONS: A protocol was
developed using available research and designed to minimize instances of
unblinding during a physiotherapy rehabilitation trial. Administrative, office,
patient and research staff procedures were included. MAIN MEASURES: Trial
questionnaires measured blind outcome assessment responses at 3 and 12 months
post surgery. The outcome assessor kept a field diary recording the events
surrounding instances of unblinding. Data underwent descriptive and content
analysis. RESULTS: Blind outcome assessment was believed successful for n = 74
(81.32%) assessments at 3-month follow-up, and n = 83 (91.21%) at 12 months.
Forty instances (n = 28 participants) of unblinding were described in the field
diary. While the main cause of unblinding was participants telling the outcome
assessor, in 12.5% of events the assessor drew the wrong conclusion regarding
group allocation. Not all unblinding events were remembered at subsequent
assessments, even in this relatively small trial. CONCLUSIONS: Blind outcome
assessment was considered achievable in this trial. Specific trial protocols
enabled blinding beliefs to be reported and instances of unblinding to be
described.

Langue : ANGLAIS