Blinding of Outcomes in Trials of Orthopaedic Trauma: An Opportunity to Enhance the Validity of Clinical Trials

BACKGROUND: Blinding personnel in randomized controlled trials is an important strategy to minimize bias and increase the validity of the results. Trials of surgical interventions present blinding challenges not seen in drug trials. How often orthopaedic trauma investigators undertake blinding, and the frequency with which they could potentially utilize blinding, remains uncertain. METHODS: We conducted a systematic review of all randomized controlled trials of orthopaedic trauma published from 1995 to 2004. Two reviewers assessed each trial for eligibility and extracted data regarding its characteristics, outcomes, reporting of blinding, and feasibility of blinding. RESULTS: We included 171 unique randomized controlled trials spanning a variety of body regions and interventions. The most commonly reported outcomes were clinical (e.g., mortality or wound infection; 91% of trials), radiographic (83%), patient-reported (66%), and physiological results (e.g., range of motion; 56%). Less than 10% of the trials in each category reported the use of blinded outcome assessors. This contrasted with blinding that investigators could have accomplished: blinding was feasible with use of simple methods such as independent assessors, concealed incisions, and masked radiographs for 89% of clinical assessors, 89% of radiographic assessors, 96% of physiological assessors, and 35% of patient-reported assessors. CONCLUSIONS: Trials in orthopaedic trauma typically measure many outcomes requiring judgment, but the individuals assessing those outcomes are seldom blinded. Investigators have the opportunity to enhance the validity of future clinical trials by incorporating simple blinding techniques.