Risk factors for work-related assaults on nurses.

Background: Work-related homicides have been the subject of considerable study, but little is known about nonfatal violence and relevant risk factors.

Methods: We surveyed 6300 Minnesota nurses who were selected randomly from the 1998 licensing database and determined their employment and occupational violence experience. In a nested case-control study, we examined environmental exposures and physical assault. Cases of assault in the previous 12 months and controls randomly selected from assault-free months were surveyed about prior-month exposures.

Results: After adjustment by multiple logistic regression, incidence of physical assault was 13.2 per 100 persons per year (95% confidence interval = 12.2-14.3). Among 310 cases and 946 control subjects, odds ratios for assault were increased: in nursing homes or long-term care facilities (2.6; 1.9-3.6), emergency departments (4.2; 1.3-12.8), and psychiatric departments (2.0; 1.1-3.7); in environments not "bright as daylight" (2.2; 1.6-2.8); and for each additional hour of shift duration (1.05; 0.99-1.11). Risks were decreased when carrying cellular telephones or personal alarms (0.3; 0.2-0.7).

Conclusions: These results may guide in-depth investigation of ways protective and risk factors can control violence against nurses.