Homelessness among psychiatric inpatients in North Rhine-Westphalia: a retrospective routine data analysis.

Background: Within the last five years the number of homeless persons in Germany has more than doubled, with many suffering from mental illnesses that require treatment. Whether the mental illness itself led to losing shelter or whether the state of being homeless increased the likelihood of developing symptoms of a mental disorder remains unclear. The current study assessed the interaction of homelessness and mental illness from a care provider perspective.

Methods: We conducted a retrospective analysis of inpatient routine data from 20 psychiatric hospitals in North Rhine-Westphalia (NRW), Germany, over a period of four years (N = 366,767 inpatient treatment cases). Patients were considered "homeless" if they had no fixed unique address.

Results: About 2.4% of the analyzed cohort was classified as homeless, with increasing tendency over the study period (+14% from 2016 to 2019). The percentage of homeless patients varied broadly between the hospitals (0.2-6.3%). Homeless patients were more often male and on average eight years younger than patients with a fixed address. Homeless patients experienced more involuntary measures (admission and restraint), had a shorter course of treatment and were more often discharged within one day. Every second homeless case was diagnosed with a substance use disorder and every third homeless case with a psychotic disorder, whereas affective disorders were diagnosed less frequently in this group. Psychiatric comorbidity occurred more often in homeless patients whereas somatic diseases did not.

Conclusions: Multiple patient-related sociodemographic and local factors are associated with homelessness of psychiatric inpatients. In addition, clinical factors differ between homeless and non-homeless patients, pointing to more severe mental illness and treatment complications (e.g., coercive measures) in homeless persons. Thus, homelessness of psychiatric inpatients can imply special challenges that need to be considered by healthcare providers and politicians, with the goal of optimizing mental and social care and the mental health outcomes of homeless persons.