Abstract
Depression is associated with increased self-harm risk, particularly in the early illness course, yet individualised predictions models remain underexplored. We aimed to develop and externally validate a prediction model for self-harm risk in people with newly-diagnosed-depression. Utilizing a territory-wide electronic health-record (EHR) database spanning Hong-Kong public healthcare services (including all public hospitals, specialists, and general outpatient clinics), we identified individuals aged ≥12 years with first-diagnosed depression between 1-January-2002 and 31-December-2021. The primary outcome was non-fatal self-harm and/or completed suicide. We developed 1-year and 3-year self-harm risk prediction models using the least absolute shrinkage and selection operator (LASSO) method and backward regression model. This population-based cohort comprised 102,863 individuals with newly-diagnosed-depression (mean age 48.22 [SD 17.78] years; 71.5% female), 2678 self-harm incidents occurred over 98,807.5 person-years (rate: 27.09 [95%CI 26.1-28.1] per 1000 person-years). Key predictors included history of self-poisoning/self-inflicted injury, past psychiatric hospitalisation, comorbid somatoform and conversion disorders, and substance use disorders, while use of lithium and antidepressants represented protective factors. In external validation cohort (n = 14,843), our model achieved good discrimination (C-statistics = 0.83 [95%CI 0.80-0.85], D = 2.35 [2.17-2.53]), near-perfect calibration (calibration slope =1.00 [0.94-1.06], O/E ratio = 1.00 [0.90-1.10]), and high accuracy (brier score = 0.02 [0.02-0.02]). Performance remained robust in age, sex-stratified subgroups and 1-year vs. 3-year self-harm prediction windows. This validated model leverages EHR data to accurately identified individuals at elevated self-harm risk post-depression diagnosis, may tailor individual-level risk estimates and facilitate timely interventions, thereby potentially averting risk escalation, in the critical window of heightened self-harm risk.
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Data availability
Data collected for this study are proprietary of the Hospital Authority of Hong Kong, which granted researchers permission and access to data. The data that support the findings of this study are available from this authority, but restrictions apply to the availability to these data (information on the cost is available from the corresponding author). The analytic codes are available from the corresponding author on request.
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Acknowledgements
The authors would like to thank the colleagues in the Hospital Authority of Hong Kong for their kind assistance in data extraction for the current investigation.
Funding
The study was supported by the Health and Medical Research Fund, Food and Health Bureau of the HKSAR government (reference number: 21222111). The funders of the study had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
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WCC, JKNC and CSMW conceptualized and designed the study. WCC contributed to the acquisition of data. WCC and JKNC oversaw the data analysis and interpreted the results. IWLC contributed to the data analysis and interpretation of the results. HKYL interpreted the data and wrote the first draft of manuscript and revised the manuscript. WCC and JKNC contributed substantially to the revision of manuscript drafts. WCC and HKYL finalized the manuscript. All authors provided critical feedback to the manuscript drafts, reviewed and approved the final manuscript.
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The study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority HK-West Cluster (UW 23-540). Since study data were anonymized and individual patient records were completely unidentifiable during the analysis, and the study was based on retrieved public health-record database, the requirement for written informed consent was waived by the Institutional Review Board. The study was conducted in accordance with the World Medical Association Declaration of Helsinki.
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Lo, H.K.Y., Chu, I.W.L., Chan, J.K.N. et al. Prediction of self-harm in people with newly-diagnosed depression: development and validation of risk prediction models. Mol Psychiatry (2026). https://doi.org/10.1038/s41380-026-03555-x
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DOI: https://doi.org/10.1038/s41380-026-03555-x


