Classification of traumatic life events and substance use among persons admitted to inpatient psychiatry in Ontario, Canada.

Background: Trauma is commonly overlooked or undiagnosed in clinical care settings. Undetected trauma has been associated with elevated substance use highlighting the need to prioritize identifying individuals with undetected trauma through common characteristics.

Objective: The purpose of this study is to identify classifications of traumatic life experiences and substance use among persons admitted to inpatient psychiatry in Ontario and to identify covariates associated with classification membership.

Study Design: A population-based retrospective cohort study was conducted using interRAI Mental Health (MH) assessment data. Individuals were included who experienced traumatic life events (N = 10,125), in Ontario, Canada between January 1, 2015, to December 31, 2019.

Results: Eight latent classes were identified that ranged from low (i.e., Class 1: Interpersonal Issues, Without Substance use) to high (i.e., Class 8: Widespread Trauma, Alcohol & Cannabis Addiction) complexity patterns of traumatic life events and substance use indicators. Classifications with similar trauma profiles were differentiated by patterns of substance use. For example, individuals in Class 2: Safety & Relationship Issues, Without Substance use and Class 3: Safety & Relationship Issues, Alcohol & Cannabis both had many estimates centered around the experience of victimization (e.g., victim of sexual assault, victim of physical assault, victim of emotional abuse). Multinomial logistic regression models highlighted additional factors associated with classifications such as homelessness, where those who were homeless were 2.09-4.02 times more likely to be in Class 6: Widespread Trauma & Substance Addiction.

Interpretation: Trauma exposures are complex and varied among persons in inpatient psychiatry and can be further differentiated by substance use patterns. These findings provide a population-based estimate of the trauma experiences of persons in inpatient settings in Ontario, Canada. Findings demonstrate the importance of using comprehensive assessment to support clinical decision making in relation to trauma and substance.