Adaptive Randomization Methods for Sequential Multiple Assignment Randomized Trials (SMARTs) via Thompson Sampling

Fuente: arXiv
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Autori principali: Norwood, Peter, Davidian, Marie, Laber, Eric
Natura: Preprint
Pubblicazione: 2024
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author Norwood, Peter
Davidian, Marie
Laber, Eric
author_facet Norwood, Peter
Davidian, Marie
Laber, Eric
contents Response-adaptive randomization (RAR) has been studied extensively in conventional, single-stage clinical trials, where it has been shown to yield ethical and statistical benefits, especially in trials with many treatment arms. However, RAR and its potential benefits are understudied in sequential multiple assignment randomized trials (SMARTs), which are the gold-standard trial design for evaluation of multi-stage treatment regimes. We propose a suite of RAR algorithms for SMARTs based on Thompson Sampling (TS), a widely used RAR method in single-stage trials in which treatment randomization probabilities are aligned with the estimated probability that the treatment is optimal. We focus on two common objectives in SMARTs: (i) comparison of the regimes embedded in the trial, and (ii) estimation of an optimal embedded regime. We develop valid post-study inferential procedures for treatment regimes under the proposed algorithms. This is nontrivial, as (even in single-stage settings) RAR can lead to nonnormal limiting distributions of estimators. Our algorithms are the first for RAR in multi-stage trials that account for nonregularity in the estimand. Empirical studies based on real-world SMARTs show that TS can improve in-trial subject outcomes without sacrificing efficiency for post-trial comparisons.
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id arxiv_https___arxiv_org_abs_2401_03268
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Adaptive Randomization Methods for Sequential Multiple Assignment Randomized Trials (SMARTs) via Thompson Sampling
Norwood, Peter
Davidian, Marie
Laber, Eric
Methodology
62P10
Response-adaptive randomization (RAR) has been studied extensively in conventional, single-stage clinical trials, where it has been shown to yield ethical and statistical benefits, especially in trials with many treatment arms. However, RAR and its potential benefits are understudied in sequential multiple assignment randomized trials (SMARTs), which are the gold-standard trial design for evaluation of multi-stage treatment regimes. We propose a suite of RAR algorithms for SMARTs based on Thompson Sampling (TS), a widely used RAR method in single-stage trials in which treatment randomization probabilities are aligned with the estimated probability that the treatment is optimal. We focus on two common objectives in SMARTs: (i) comparison of the regimes embedded in the trial, and (ii) estimation of an optimal embedded regime. We develop valid post-study inferential procedures for treatment regimes under the proposed algorithms. This is nontrivial, as (even in single-stage settings) RAR can lead to nonnormal limiting distributions of estimators. Our algorithms are the first for RAR in multi-stage trials that account for nonregularity in the estimand. Empirical studies based on real-world SMARTs show that TS can improve in-trial subject outcomes without sacrificing efficiency for post-trial comparisons.
title Adaptive Randomization Methods for Sequential Multiple Assignment Randomized Trials (SMARTs) via Thompson Sampling
topic Methodology
62P10
url https://arxiv.org/abs/2401.03268