Ethics, consent and blinding: lessons from a placebo/sham controlled CPAP crossover trial

Area of Science:

• Medical Devices
• Sleep Medicine
• Clinical Trials

Background:

• Device-based treatments for obstructive sleep apnea (OSA) present unique clinical trial design challenges.
• Continuous positive airway pressure (CPAP) is a highly effective OSA treatment.
• Assessing blinding efficacy in device trials requires careful methodology.

Purpose of the Study:

• To evaluate patient and staff blinding in a randomized crossover trial of CPAP versus placebo for OSA.
• To assess the impact of non-disclosure of placebo on patient blinding.
• To determine the rates and accuracy of staff unblinding.

Main Methods:

• A randomized crossover trial comparing CPAP and placebo therapy for OSA.
• Patients (n=30) underwent semi-structured interviews to assess suspicion of ineffective therapy.
• Staff unblinding was monitored via questionnaires after patient encounters.

Main Results:

• Patient blinding was successful, likely due to non-disclosure of placebo.
• 73% of patients felt they would have been unblinded if full disclosure occurred at consent.
• Staff unblinding occurred in 6% of encounters, with correct device identification in 69% of those instances.

Conclusions:

• Achieving patient blinding in CPAP trials may necessitate withholding full disclosure of placebo.
• Investigator blinding remains a significant challenge in device-based clinical trials.
• Ethical considerations regarding non-disclosure may impact the feasibility of such research.