Risk factors of psychiatric hospitalization of military service persons in Taiwan: Preliminary results from unsupervised clustering techniques

Background: To understand the discrepancies of the use of mental health providers among different military ranks and/or compulsory/voluntary military services especially of the psychiatry admission during active services. Methods: We collected military medical records of one military psychiatry teaching hospital of north Taiwan from 2012 to 2015. All 3,513 samples were divided into three groups ─ enlisted females (EFs), enlisted males, and drafted males (DMs). The outcome measurement was the time period from the date of enlisted or drafted to the first psychiatric admission (E-A period). After comparing baseline characteristics and E-A period among three groups, we applied unsupervised clustering techniques, exhaustive Chi-squared automatic interaction detector, to cluster samples based on their military ranks and compulsory/voluntary service. Results: In general, the EF group showed the longest E-A period and the DM group the shortest. The most common diagnosis was major depression followed by anxiety or other nonpsychiatric disorders. The privates and recruits showed shorter E-A periods, and the younger enlistment age of officers showed the longer E-A period if we clustered based on military ranks. Those who entered army due to obligation showed shorter E-A period and those males who enlisted voluntarily at age over 22.5 years also showed shorter E-A period. Conclusion: This study demonstrates potential clusters associating with psychiatry admission in military. But, we caution that the findings here should be treated as preliminary