Epidemiology of violent injury in emergency rooms among people experiencing homelessness in san francisco

Background: San Francisco has a large homeless population; in this 46-square mile city, 5,728 were estimated to be homeless in 2011. Many more people are transiently housed in single room occupancy hotels, intermittently without shelter. People experiencing homelessness are high users of emergency department services, and also have high rates of violent injury. To date, no study has described housing status and outcomes associated with interpersonal violence among this population. We hypothesized that housing status is an independent risk factor for injury recidivism. Methods: A cohort of adult patients admitted to the Emergency Department at our Trauma Center in 2010 – 2011 after violent injury was evaluated. Housing status and demographic data was obtained using admission information. Three categories were used for comparison: Housed, Transitionally-Housed, and Homeless. Outcomes assessed included injury characteristics and injury recidivism. Sixty-three percent of transiently-housed patients were injured by stabbings, 18% by gun violence; fifty-one percent of homeless patients were injured by stabbings, 32% by gun violence. Compared to those with stable housing, transiently-housed patients were 3.2 times more likely to be a violent injury recidivist, compared to homeless patients, who were 3.8 times as likely (p<.001). Homeless individuals are more likely to be a recidivist compared to those with transient housing (p<.01). Conclusions: High rates of violence and injury recidivism exist among the homeless in San Francisco. Our study demonstrates this population is extremely vulnerable to interpersonal violence. Improving access to housing, substance abuse treatment and mental health services should be emphasized in prevention efforts.