Encounter-based randomization did not result in contamination in a shared decision-making trial: a secondary analysis

Area of Science:

• Clinical Trials
• Health Services Research
• Patient-Centered Care

Background:

• Shared decision-making (SDM) tools aim to improve patient-clinician communication.
• Contamination, where control groups are exposed to interventions, can bias randomized trials.
• Assessing contamination is crucial for the validity of encounter-randomized trials.

Purpose of the Study:

• To quantify contamination in an encounter-randomized trial of an SDM tool.
• To evaluate tool, functional, and learned contamination in usual care encounters.

Main Methods:

• An encounter-randomized trial design was used.
• Contamination was assessed at three levels: tool presence, functional use, and learned skills (OPTION-12 score).
• The interaction between tool exposure and contamination was analyzed.

Main Results:

• Of 411 usual care encounters, the SDM tool was present in only 2.2%.
• No significant functional or learned contamination was observed.
• No significant interaction was found between tool exposure and contamination levels.

Conclusions:

• Random assignment to an SDM tool did not lead to contamination in usual care encounters.
• The findings support the validity of the encounter-randomized trial design for evaluating SDM tools.
• Contamination does not appear to be a significant issue in this context.