Challenges and recommendations for blinding in behavioral interventions illustrated using a case study of a behavioral intervention to lower blood pressure.

OBJECTIVE: To describe the challenges to blinding in behavioral interventions, specifically those for asymptomatic medical conditions, where the intervention is through counseling, and to provide recommendations for achieving blinding in behavioral randomized controlled trials (RCTs).
METHODS: This paper reviews the challenges of preserving blinding in behavioral RCTs with a focus on interventions for asymptomatic medical conditions. This is illustrated using a case study of an ongoing behavioral intervention to improve hypertension control.
RESULTS: In contrast to easily keeping study investigators and participants masked to treatment assignment through the use of identical pills or sham treatments, the need to have differing levels of blinding among study personnel and participants in randomized behavioral intervention trials is presented. Recommendations for achieving this are provided.
CONCLUSIONS: Despite the challenges inherent in behavioral interventions, it is possible to achieve differing levels of blinding across study personnel and participants to minimize bias and generate valid data in RCTs that test interventions for asymptomatic medical conditions such as hypertension. Modifications may be needed for RCTs in symptomatic medical conditions. PRACTICE IMPLICATIONS: Researchers designing behavioral RCTs should be aware of the challenges to blinding all staff and study participants, and plan to have procedures in place to standardize outcome data collection and intervention delivery without compromising the varying levels of blinding. The challenges and recommendations described may need modifications in behavioral intervention studies for symptomatic conditions.