Crowding and violence on psychiatric wards: explanatory models.

OBJECTIVE: Violence is widely prevalent on acute-care psychiatric wards, and crowding has been identified as a major risk factor. This paper explores why patients may respond to crowding with violence. METHOD: We carried out a literature review on Medline, using the key words "violence" and "crowding." We conducted an additional hand search of the references collected from the reviewed papers. RESULTS: Factors specific to the relation between crowding on acute-care inpatient psychiatric wards and violence can be divided under the following headings: 1) patient density, privacy, and control; 2) ward architecture; 3) the social organization of psychiatric wards; 4) interpersonal space; 5) phylogenic theories; and 6) anthropological theories of human behaviour. CONCLUSIONS: We offer explanatory models for this relation and suggest strategies to counter the effects of crowding. Recommendations are made for future studies.