Overcrowding in psychiatric wards and physical assaults on staff: data-linked longitudinal study.

BACKGROUND Patient overcrowding and violent assaults by patients are two major problems in psychiatric healthcare. However, evidence of an association between overcrowding and aggressive behaviour among patients is mixed and limited to small-scale studies. AIMS This study examined the association between ward overcrowding and violent physical assaults in acute-care psychiatric in-patient hospital wards. METHOD Longitudinal study using ward-level monthly records of bed occupancy and staff reports of the timing of violent acts during a 5-month period in 90 in-patient wards in 13 acute psychiatric hospitals in Finland. In total 1098 employees (physicians, ward head nurses, registered nurses, licensed practical nurses) participated in the study. The outcome measure was staff reports of the timing of physical assaults on both themselves and ward property. RESULTS We found that 46% of hospital staff were working in overcrowded wards, as indicated by >10 percentage units of excess bed occupancy, whereas only 30% of hospital personnel were working in a ward with no excess occupancy. An excess bed occupancy rate of >10 percentage units at the time of an event was associated with violent assaults towards employees (odds ratio (OR) = 1.72, 95% CI 1.05-2.80; OR = 3.04, 95% CI 1.51-6.13 in adult wards) after adjustment for confounding factors. No association was found with assaults on ward property (OR = 1.06, 95% CI 0.75-1.50). CONCLUSIONS These findings suggest that patient overcrowding is highly prevalent in psychiatric hospitals and, importantly, may increase the risk of violence directed at staff.