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 high-quality 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: Adaptive treatment strategies; Dynamic treatment regimens or regimes; Experimental design; Individualized or personalized behavioral interventions; Timing and sequencing of intervention components.

Figures

Fig 1

a. This is one example of an adaptive intervention for weight loss. Response status is defined as losing ≥5 lbs by the end of the 5th weekly session on IBT. Total treatment occurs over 26 weeks. b. This is a second example of an adaptive intervention for weight loss. This example builds on the example in Fig. 1. In this example, the duration of initial IBT is individualized based on baseline information about emotional eating. IBT individualized behavioral treatment, MR meal replacements, ACT acceptance and commitment therapy (adapted for weight loss)

Fig 2

This is an example sequential multiple assignment randomized trial (SMART) design for developing a weight loss intervention. Four adaptive interventions are embedded within this SMART (see Table 2). N sample of overweight or obese adult participants, R randomization, with probability 1/2, IBT individualized behavioral treatment, MR meal replacements, ACT acceptance and commitment therapy (adapted for weight loss)

Fig 3

This is a variation of the example SMART in Fig. 3 in which the decision to provide 5 vs 10 weeks of initial IBT occurs at the end of 5 weeks on IBT instead of at baseline. N sample of overweight or obese adult participants, R randomization, with probability 1/2, IBT individualized behavioral treatment, MR meal replacements, ACT acceptance and commitment therapy (adapted for weight loss)