Introduction to SMART designs for the development of adaptive interventions: with application to weight loss research

Abstract

The management of many health disorders often entails a sequential, individualized approach whereby treatment is adapted and readapted over time in response to the specific needs and evolving status of the individual. Adaptive interventions provide one way to operationalize the strategies (e.g., continue, augment, switch, step-down) leading to individualized sequences of treatment. Often, a wide variety of critical questions must be answered when developing a highquality adaptive intervention. Yet, there is often insufficient empirical evidence or theoretical basis to address these questions. The Sequential Multiple Assignment Randomized Trial (SMART)-a type of research design-was developed explicitly for the purpose of building optimal adaptive interventions by providing answers to such questions. Despite increasing popularity, SMARTs remain relatively new to intervention scientists. This manuscript provides an introduction to adaptive interventions and SMARTs. We discuss SMART design considerations, including common primary and secondary aims. For illustration, we discuss the development of an adaptive intervention for optimizing weight loss among adult individuals who are overweight. KEYWORDS

Predicting dropout in dietary weight loss trials using demographic and early weight change characteristics: Implications for trial design

“…As the amount of the weight loss in the first month was independent of treatment assignment in this analysis it is possible that this initial response is related more to participant characteristics than treatment effects. New design methods such as sequential multiple assignment should be considered where the initial response is part of the study design 26 . Here all participants are randomised at least once, however those who fail to respond at a predefined time point are further randomised into more than one treatment option.…”

“…Adaptive designs where randomisation of incoming subjects in based on the early weight loss of existing subjects could also be considered 27 . The potential for the use of these designs in weight loss, sample size estimation and analysis is covered in detail in Almirall et al 26 .…”

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“…Given the lack of intervention studies for symptom clusters, the optimization of a multicomponent intervention prior to the initiation of an RCT should result in a more effective, economical, efficient, and scalable intervention. One approach to achieve this goal is to use the multiphase optimization strategy (MOST) that is a comprehensive framework for the development, optimization, and evaluation of behavioral interventions, including dynamic treatment regimens (76)(77)(78)(79). An important tool for optimization of the treatment regimen is the sequential, multiple assignment, randomized trial (SMART).…”

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“…The fact that engagement dropped substantially early within the constraint of a randomized controlled trial suggests that a more effective intervention, that automatically adapts to behavior and self-measured engagement such as using just in time adaptive design, may be needed. [34,35] …”