Abstract
OBJECTIVE: To evaluate the use of existing practice control groups in randomized controlled trials of behavioral interventions and the role of extrinsic health care services in the design and conduct of behavioral trials. METHOD: Selective qualitative review. RESULTS: Extrinsic health care services, also known as nonstudy care, have important but under-recognized effects on the design and conduct of behavioral trials. Usual care, treatment-as-usual, standard of care, and other existing practice control groups pose a variety of methodological and ethical challenges, but they play a vital role in behavioral intervention research. CONCLUSIONS: This review highlights the need for a scientific consensus statement on control groups in behavioral trials.