Suicide and unintentional injury mortality among homeless people: a Danish nationwide register-based cohort study

Abstract

Homeless people have elevated mortality, especially due to external causes. We aimed to examine suicide and unintentional injury mortality levels and identify predictors in the homeless population. A nationwide, register-based cohort study of homeless people aged 16 years and older was carried out using the Danish Homeless Register, 1999-2008. In all, 32 010 homeless people (70.5% men) were observed. For men, the mortality rate was 174.4 [95% confidence interval (CI) = 150.6-198.1] per 100 000 person-years for suicide and 463.3 (95% CI = 424.6-502.0) for unintentional injury. For women, the corresponding rates were 111.4 (95% CI = 81.7-141.1) for suicide and 241.4 (95% CI = 197.6-285.1) for unintentional injury. Schizophrenia spectrum, affective, personality and substance use disorders were strongly associated with increased risk of suicide; the highest risk estimates were found for schizophrenia spectrum disorders among both men [hazard ratio (HR) = 3.1, 95% CI = 2.0-4.9] and women (HR = 15.5, 95% CI = 4.5-54.0). Alcohol and drug use disorders were predictors of death by unintentional injury for both men and women, whereas schizophrenia spectrum disorders and personality disorders were only significant predictors among men; the highest risk estimates were found for drug use disorders among men (HR = 2.2, 95% CI = 1.8-2.8) and women (HR = 3.1, 95% CI = 1.8-5.4). A history of psychiatric admission and emergency room contact were predictors for dying by suicide and unintentional injury. People in the homeless shelter population with a history of a psychiatric disorder constitute a high-risk group regarding the elevated suicide and unintentional injury mortality.