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Main Authors: Li, Siqi, Hong, Chuan, Tian, Ziye, Leong, Benjamin Sieu-Hon, Nakagawa, Koshi, Tanaka, Hideharu, Shin, Sang Do, Dai, Khuong Quoc, Son, Do Ngoc, Ong, Marcus Eng Hock, Liu, Nan, Liu, Molei
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.24212
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author Li, Siqi
Hong, Chuan
Tian, Ziye
Leong, Benjamin Sieu-Hon
Nakagawa, Koshi
Tanaka, Hideharu
Shin, Sang Do
Dai, Khuong Quoc
Son, Do Ngoc
Ong, Marcus Eng Hock
Liu, Nan
Liu, Molei
author_facet Li, Siqi
Hong, Chuan
Tian, Ziye
Leong, Benjamin Sieu-Hon
Nakagawa, Koshi
Tanaka, Hideharu
Shin, Sang Do
Dai, Khuong Quoc
Son, Do Ngoc
Ong, Marcus Eng Hock
Liu, Nan
Liu, Molei
contents Deploying clinical prediction models across healthcare systems often fails when key training covariates are unavailable at deployment and labeled outcomes are limited in the target domain. For example, high-performing models for out-of-hospital cardiac arrest (OHCA) rely on detailed prehospital measurements routinely collected in high-resource settings but unavailable in many international registries. Existing methods either discard missing covariates, sacrificing predictive information, or rely on untestable assumptions about their target distribution. We propose DRUM (\underline{D}istributionally \underline{R}obust \underline{U}nsupervised transfer learning with structurally \underline{M}issing covariates), a framework that transfers prediction models to target populations where certain covariates are structurally absent and outcome labels are unavailable. DRUM partitions covariates into shared components ($X$), observed across all settings, and missing components ($A$), observed only in the source. Rather than imputing missing covariates, DRUM optimizes worst-case predictive performance over the unknown target distribution of $A \mid X$ using a neural network generator, with a robustness parameter controlling allowable deviation from the source conditional. We further develop a bias correction procedure that reduces sensitivity to nuisance estimation error. Simulations show substantial improvements in both mean and worst-case prediction error under distribution shift. Applied to cross-national OHCA prediction, transferring models from a US registry to multiple Asian registries where prehospital variables are unrecorded, DRUM yields better-calibrated predictions and improved clinical classification performance across sites.
format Preprint
id arxiv_https___arxiv_org_abs_2605_24212
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Distributionally Robust Transfer Learning with Structurally Missing Covariates, with Application to Cross-National Cardiac Arrest Prediction
Li, Siqi
Hong, Chuan
Tian, Ziye
Leong, Benjamin Sieu-Hon
Nakagawa, Koshi
Tanaka, Hideharu
Shin, Sang Do
Dai, Khuong Quoc
Son, Do Ngoc
Ong, Marcus Eng Hock
Liu, Nan
Liu, Molei
Applications
Artificial Intelligence
Machine Learning
Deploying clinical prediction models across healthcare systems often fails when key training covariates are unavailable at deployment and labeled outcomes are limited in the target domain. For example, high-performing models for out-of-hospital cardiac arrest (OHCA) rely on detailed prehospital measurements routinely collected in high-resource settings but unavailable in many international registries. Existing methods either discard missing covariates, sacrificing predictive information, or rely on untestable assumptions about their target distribution. We propose DRUM (\underline{D}istributionally \underline{R}obust \underline{U}nsupervised transfer learning with structurally \underline{M}issing covariates), a framework that transfers prediction models to target populations where certain covariates are structurally absent and outcome labels are unavailable. DRUM partitions covariates into shared components ($X$), observed across all settings, and missing components ($A$), observed only in the source. Rather than imputing missing covariates, DRUM optimizes worst-case predictive performance over the unknown target distribution of $A \mid X$ using a neural network generator, with a robustness parameter controlling allowable deviation from the source conditional. We further develop a bias correction procedure that reduces sensitivity to nuisance estimation error. Simulations show substantial improvements in both mean and worst-case prediction error under distribution shift. Applied to cross-national OHCA prediction, transferring models from a US registry to multiple Asian registries where prehospital variables are unrecorded, DRUM yields better-calibrated predictions and improved clinical classification performance across sites.
title Distributionally Robust Transfer Learning with Structurally Missing Covariates, with Application to Cross-National Cardiac Arrest Prediction
topic Applications
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2605.24212