Objective: To provide guidelines for conducting independent assessments in randomized controlled trials (RCTs) of rehabilitation. The article aims to assist those who plan to put independent assessment into practice and to be an introduction for those who are new to independent assessment.
Issues: Possible causes of unblinding to group allocation are discussed, such as unblinding by other people, the environment, patients and assessors themselves. Other issues discussed in this paper are bias during assessment and monitoring levels of unblinding.
Conclusion: The importance of monitoring levels of unblinding is stressed. Although it may not be possible to always keep an assessor blind in RCTs of rehabilitation, we should strive for perfection. It is therefore advocated that levels of unblinding should be reported.