Age structure at diagnosis affects aggression in a psychiatric inpatient population: age structure affecting inpatient aggression.

Study of inpatient aggression in psychiatric inpatient units (PIUs), where vulnerable patients interact intensely in small groups, is hampered by a lack of systematic monitoring of aggressive events in the context of group dynamics. Our current study examines the relationship between aggression and group structure in the PIU of a general tertiary-care hospital over a 9-month period. The severity of aggression was monitored daily using the Overt Aggression Scale (OAS). Clinical data including the daily number and mean age of subpopulations with different diagnoses were acquired. Cross-correlation function and autoregressive integrated moving average modeling were used to assess the effects of various group structure parameters on the incidence of aggressive events in the PIU. The daily total OAS score correlated positively with the daily mean age of patients with schizophrenia and bipolar disorder. By contrast, the OAS total score demonstrated a negative correlation with the daily mean age of patients with major depression. The age of the patients at diagnosis is an important group structure that affects the incidence of aggression in a PIU.