Involuntary admission (IA) for psychiatric treatment has a history of controversial discussions. We aimed to describe characteristics of a cohort of involuntarily compared to voluntarily admitted patients regarding clinical and socio-demographic characteristics before and after implementation of the new legislation.

In this observational cohort study, routine data of 15’125 patients who were admitted to the University Hospital of Psychiatry Zurich between 2008 and 2016 were analyzed using a series of generalized estimating equations.

At least one IA occurred in 4’560 patients (30.1%). Of the 31’508 admissions 8’843 (28.1%) were involuntary. In the final multivariable model, being a tourist (OR = 3.5) or an asylum seeker (OR = 2.3), having a schizophrenic disorder (OR = 2.1), or a bipolar disorder (OR = 1.8) contributed most to our model. Male gender, higher age, prescription of neuroleptics (all OR < 2.0) as well as having a depressive disorder, prescription of psychotherapy, prescription of antidepressants and admission after implementation of the new legislation (all OR > 0.6) were also weakly associated with IA.

Besides schizophrenic or bipolar disorders, a small group of patients had an increased risk for IA due to non-clinical parameters (i.e. tourists and asylum seekers). Knowledge about risk factors should be used for the development of multi-level strategies to prevent frequent (involuntary) hospitalizations in patients at risk. On the organizational level, we could show that the new legislation decreased the risk for IA, and therefore may have succeeded in strengthening patient autonomy.