Violence and aggression in psychiatric units.

OBJECTIVE: To help predict aggressive and violent behaviors, the frequency and types of these behaviors in acute psychiatric inpatient settings were examined, and potential interactions between staffing and patient mix and rates of the behaviors were explored.
METHODS: Data on violent incidents were gathered prospectively in three adult acute psychiatric units in a general hospital and two units in a primary psychiatric hospital in Sydney, Australia. Staff recorded violent and aggressive incidents, which were ranked on an 8-level scale. They also completed weekly reports of staffing levels and patient mix. Poisson regression analysis was used to calculate relative rates, 95 percent confidence intervals, and p values.
RESULTS: A total of 1,289 violent incidents were recorded over a seven-month period. Based on the scale, 58 percent of the incidents were serious. Seventy-eight percent were directed toward nursing staff. Complex relationships between staffing, patient mix, and violence were found. Relative risk increased with more nursing staff (of either sex), more nonnursing staff on planned leave, more patients known to instigate violence, a greater number of disoriented patients, more patients detained compulsorily, and more use of seclusion. The relative risk decreased with more young staff (under 30 years old), more nursing staff with unplanned absenteeism, more admissions, and more patients with substance abuse or physical illness. In total these factors accounted for 62 percent of the variance in violence.
CONCLUSIONS: Violent incidents in psychiatric settings are a frequent and serious problem. Incidents appear to be underreported, and the seriousness of an incident does not guarantee it will be reported.