Objective: Some recent studies suggest that double blinding should not be considered a validity criterion in randomized controlled trials (RCTs) on real-life circumstances. This study aims to assess whether blinding vs. nonblinding have been analyzed conceptually in the rehabilitation literature. Propositions on the role of blinding in RCTs on rehabilitation are presented based on the conceptual analysis.
Design: Study questions, literature search strategy, and inclusion and exclusion criteria for the original studies were formulated. A health science librarian carried out the literature search. Eligibility was assessed and data extraction was performed by two independent researchers.
Results: The literature search identified a total of 1052 citations, of which 13 studies fulfilled the inclusion criteria. None of the included studies answered our research questions, and thus we were unable to extract any relevant data.
Conclusions: The ideas on blinding vs. nonblinding in RCTs have not been considered in the rehabilitation research literature. This conceptual systematic review proposes that a physical therapy modality is a single core element, and when the study question is on effectiveness of this single core element itself, double blinding in an RCT is indicated. In all other RCTs in rehabilitation, double blinding is not indicated and double blinding should not be considered a criterion for the assessment of risk of bias.