Factors Underlying Patient and Surgeon Willingness to Participate in a Placebo Surgery Controlled trial: A Qualitative Investigation.

Objective: To investigate the factors underlying willingness to participate in a hypothetical trial among patients and surgeons, to inform the design of future placebo surgery controlled trials. Background: Placebo surgery controlled trials are the gold standard for testing the efficacy of surgical procedures. However, these trials commonly fail to meet the target sample size and terminate underpowered. Methods: From October 2019 to July 2020, eligible patients were identified from the orthopedic waiting list at a single tertiary hospital and surgeons were identified from orthopedic clinics at three tertiary hospitals in Australia. Qualitative interviews explored factors underlying willingness to participate in a hypothetical trial, including understanding of trial concepts; attitudes; and trial design preferences. Data collection and analysis were conducted in parallel. Recruitment ceased when no new concepts emerged. Interview data were analyzed using reflexive thematic analysis. Results: The majority of surgeons and only a few patients indicated a willingness to participate in a placebo surgery controlled trial. Factors underlying willingness were captured in four themes: (1) Understanding and attitudes toward placebo; (2) Attitudes towards randomization/perception of equipoise; (3) Perception of risk; and (4) Ethical concerns. Conclusions: To optimize recruitment in the future, trialists may consider embedding strategies into the recruitment process that validate patients' symptoms, encourage an altruistic mindset, address surgeon biases, and involve surgeons in explaining trial concepts to patients. Trialists may also consider designing three arm trials that meet surgeons' preferences for a "low" and "high" fidelity placebo.