Challenges and recommendations for avoiding bias while testing behavioral interventions for chronic medical conditions

While the randomized, double-blind, placebo-controlled study is the gold standard for biomedical intervention studies, blinding is far more difficult to conduct with a behavioral intervention for a chronic medical condition, where behavior change is targeted through counseling rather than through a medical intervention such as a pharmacological intervention. In double-blind pharmaceutical randomized controlled trials (RCTs), all study personnel who interact with patients are typically blinded to group assignment. In contrast, double-blinding is difficult in behavioral interventions. Maintaining single blindness, where researchers but not patients are blind to group assignment, may not even be possible in some behavioral RCTs. Rather than keeping study investigators and participants masked to treatment assignment, there are generally differing levels of blinding among various study personnel and participants in randomized behavioral intervention trials. For example, the counselors delivering the behavioral intervention may be blinded to some aspects of the study like the study hypotheses or the outcome measures, while the personnel collecting outcome measure data may be blinded to other aspects such as treatment allocation. The unique challenges of maintaining blinding in a behavioral RCT, in particular those testing interventions for asymptomatic medical conditions, will be enumerated, and examples and recommendations from our ongoing study of a behavioral stage-matched intervention for uncontrolled hypertension will be discussed.