A Review of Methods and Practices for Missing Data in Sequential Multiple Assignment Randomized Trials (SMARTs): An Ancillary Study of a Scoping Review

Fuente: arXiv
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Autori principali: Freeman, Nikki L. B., Yu, Chenyao, Hoch, Margaret, Browder, Sydney, Hammill, Bradley G., Kenny, Avi, Anstrom, Kevin J., Kosorok, Michael R.
Natura: Preprint
Pubblicazione: 2026
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author Freeman, Nikki L. B.
Yu, Chenyao
Hoch, Margaret
Browder, Sydney
Hammill, Bradley G.
Kenny, Avi
Anstrom, Kevin J.
Kosorok, Michael R.
author_facet Freeman, Nikki L. B.
Yu, Chenyao
Hoch, Margaret
Browder, Sydney
Hammill, Bradley G.
Kenny, Avi
Anstrom, Kevin J.
Kosorok, Michael R.
contents Background: Missing data poses an acute threat to sequential multiple assignment randomized trial (SMART) analyses because of the sequential treatment structure and response-dependent re-randomization. Objectives: This study aimed to (1) review the current statistical methods for handling missing data in SMARTs, and (2) characterize how missing data is reported and handled in published SMARTs. Methods: We conducted a narrative review of statistical methods developed for missing data in SMARTs. Additionally, we conducted a pre-specified secondary extraction of a previously published scoping review of SMARTs focused on missing data. Extraction captured attrition rates, methods for handling missingness, and planned versus performed missing data analyses. Results: Seven methodological papers were identified; nearly all assume missing at random (MAR), and only one addresses the full set of SMART-specific missingness types. Across 30 published SMARTs, median overall attrition was 18.1% (range 0.6%-56.5%). Methods used to address missing data were described in 80% of the manuscripts; mixed-model methods were most common (30%). Among 14 studies with paired protocols, sensitivity analyses were pre-specified in 2 (14%). Conclusions: SMART-specific methodology for missing data is limited, and a substantial gap exists between available methodology and current SMART practice.
format Preprint
id arxiv_https___arxiv_org_abs_2604_23866
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Review of Methods and Practices for Missing Data in Sequential Multiple Assignment Randomized Trials (SMARTs): An Ancillary Study of a Scoping Review
Freeman, Nikki L. B.
Yu, Chenyao
Hoch, Margaret
Browder, Sydney
Hammill, Bradley G.
Kenny, Avi
Anstrom, Kevin J.
Kosorok, Michael R.
Methodology
Background: Missing data poses an acute threat to sequential multiple assignment randomized trial (SMART) analyses because of the sequential treatment structure and response-dependent re-randomization. Objectives: This study aimed to (1) review the current statistical methods for handling missing data in SMARTs, and (2) characterize how missing data is reported and handled in published SMARTs. Methods: We conducted a narrative review of statistical methods developed for missing data in SMARTs. Additionally, we conducted a pre-specified secondary extraction of a previously published scoping review of SMARTs focused on missing data. Extraction captured attrition rates, methods for handling missingness, and planned versus performed missing data analyses. Results: Seven methodological papers were identified; nearly all assume missing at random (MAR), and only one addresses the full set of SMART-specific missingness types. Across 30 published SMARTs, median overall attrition was 18.1% (range 0.6%-56.5%). Methods used to address missing data were described in 80% of the manuscripts; mixed-model methods were most common (30%). Among 14 studies with paired protocols, sensitivity analyses were pre-specified in 2 (14%). Conclusions: SMART-specific methodology for missing data is limited, and a substantial gap exists between available methodology and current SMART practice.
title A Review of Methods and Practices for Missing Data in Sequential Multiple Assignment Randomized Trials (SMARTs): An Ancillary Study of a Scoping Review
topic Methodology
url https://arxiv.org/abs/2604.23866