Homelessness among adults receiving Australian public mental health case management: a retrospective longitudinal cohort study using the Gelberg–Andersen model

Homelessness is common among people with severe and persistent mental health conditions, yet Australia has limited longitudinal, theory-guided evidence on vulnerability factors associated with homelessness in public mental health case management. This study applied the Gelberg–Andersen Behavioural Model for Vulnerable Populations to examine the contribution of predisposing characteristics, enabling resources, and need to homelessness status across service contacts.We conducted a retrospective longitudinal cohort study of 2,047 adults aged 18–65 years receiving public mental health community case management in Gold Coast HHS, Queensland, Australia, during 2021–2022. We analysed 15,135 time-stamped service-contact events using hierarchical mixed-effects logistic regression with predictors entered in Gelberg–Andersen blocks. Overall, 33.2% experienced homelessness at least once and 54.8% had an inpatient admission. Model fit improved with enabling resources and further with need variables. Private income/employment was strongly protective, while acute and extended inpatient admissions, aggression/overactivity, and substance use were independently associated with higher odds of homelessness status.Homelessness was patterned across multiple Gelberg–Andersen domains, with enabling resources and need adding explanatory value beyond predisposing characteristics. Although associations were neither causal nor predictive, findings highlight hospital interfaces, enabling supports, including income/employment and legal-support transitions, and behavioural needs as important service-planning targets.