Exploratory Hidden Markov Factor Models for Longitudinal Mobile Health Data: Application to Adverse Posttraumatic Neuropsychiatric Sequelae

TL;DR

This paper introduces exploratory hidden Markov factor models with a specialized algorithm to analyze longitudinal mobile health data, aiming to identify neuropsychiatric states and transitions post-trauma, reducing reliance on subjective reports.

Contribution

The paper develops a novel modeling approach and estimation algorithm tailored for longitudinal mobile health data to study neuropsychiatric sequelae after trauma.

Findings

Model effectively identifies APNS states from mobile data.

Simulation shows accurate parameter estimation and model selection.

Application demonstrates practical utility in real-world trauma data.

Abstract

Adverse posttraumatic neuropsychiatric sequelae (APNS) are common among veterans and millions of Americans after traumatic exposures, resulting in substantial burdens for trauma survivors and society. Despite numerous studies conducted on APNS over the past decades, there has been limited progress in understanding the underlying neurobiological mechanisms due to several unique challenges. One of these challenges is the reliance on subjective self-report measures to assess APNS, which can easily result in measurement errors and biases (e.g., recall bias). To mitigate this issue, in this paper, we investigate the potential of leveraging the objective longitudinal mobile device data to identify homogeneous APNS states and study the dynamic transitions and potential risk factors of APNS after trauma exposure. To handle specific challenges posed by longitudinal mobile device data, we developed exploratory hidden Markov factor models and designed a Stabilized Expectation-Maximization algorithm for parameter estimation. Simulation studies were conducted to evaluate the performance of parameter estimation and model selection. Finally, to demonstrate the practical utility of the method, we applied it to mobile device data collected from the Advancing Understanding of RecOvery afteR traumA (AURORA) study.