Incorporating Participants' Welfare into Sequential Multiple Assignment Randomized Trials

TL;DR

This paper introduces SMART-EXAM, a new SMART design that incorporates participant preferences and predicted effects to enhance welfare and optimize treatment regimes in clinical trials.

Contribution

The paper proposes SMART-EXAM, a novel SMART design that improves participant welfare by integrating preferences and predictions into the randomization process.

Findings

SMART-EXAM improves participant welfare compared to conventional SMART.

SMART-EXAM maintains the ability to identify optimal dynamic treatment regimes.

Application to ADHD data demonstrates practical utility.

Abstract

Dynamic treatment regimes (DTRs) are sequences of decision rules that recommend treatments based on patients' time-varying clinical conditions. The sequential multiple assignment randomized trial (SMART) is an experimental design that can provide high-quality evidence for constructing optimal DTRs. In a conventional SMART, participants are randomized to available treatments at multiple stages with balanced randomization probabilities. Despite its relative simplicity of implementation and desirable performance in comparing embedded DTRs, the conventional SMART faces inevitable ethical issues including assigning many participants to the empirically inferior treatment or the treatment they dislike, which might slow down the recruitment procedure and lead to higher attrition rates, ultimately leading to poor internal and external validities of the trial results. In this context, we propose a SMART under the Experiment-as-Market framework (SMART-EXAM), a novel SMART design that holds the potential to improve participants' welfare by incorporating their preferences and predicted treatment effects into the randomization procedure. We describe the steps of conducting a SMART-EXAM and evaluate its performance compared to the conventional SMART. The results indicate that the SMART-EXAM can improve the welfare of the participants enrolled in the trial, while also achieving a desirable ability to construct an optimal DTR when the experimental parameters are suitably specified. We finally illustrate the practical potential of the SMART-EXAM design using data from a SMART for children with attention-deficit/hyperactivity disorder (ADHD).