Objective: Complex physical interventions are widely used in physiotherapy, despite doubts over the validity of clinical trial results due to lack of credible shams. Credible shams are critically needed, so too, therefore, is a process by which they can be developed. The authors used a novel methodology to develop and test blinding protocols for dry needling, a complex physical intervention for which blinding is particularly difficult.
Design: The research design was a practical three-day workshop influenced by Participatory Action Research, which uses iteration and reflection to solve a problem.
Participants: Five multidisciplinary experts (researchers, clinicians, technician, magician) were invited. Healthy volunteers ('recipients', n=17) and accredited physiotherapists (n=6) were recruited to enable testing of blinding strategies.
Main outcome measures: Primary outcomes were expert opinion on the potential to blind recipients/therapists for (1) individual blinding strategies, and (2) entire blinding protocols. Secondary outcomes included recipient/therapist blinding effectiveness and acceptability.
Results: Experts iteratively developed 11 blinding protocols involving 22 blinding strategies. Experts rated 18 of the blinding strategies to 'definitely have potential' and identified four categories: knowledge of the sham, clinical interaction, disinformation, and sensation. Recipient and therapist blinding became more successful as the protocols evolved.
Conclusions: Credible shams capable of simultaneous recipient and therapist blinding have been regarded to be impossible in dry needling. The preliminary success of the devised protocols suggest that our novel approach may be a crucial step in sham development. Improvements in expert rankings and blinding effectiveness as the protocols progressed support the value of this workshop approach.
Keywords: Blinding; Clinical trials; Dry needling; Placebo; Sham; Workshop.
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