Psychiatric disorders and mortality among people in homeless shelters in Denmark: a nationwide register-based cohort study.

BACKGROUND: The increased mortality of homeless people compared with non-homeless people might be linked to psychiatric disorders. However, homeless people are, because of their insufficient accommodation, difficult to sample and monitor, which has limited previous studies. We aimed to assess registered psychiatric disorders, mortality, and predictors of mortality in the homeless shelter population in Denmark.

METHODS: We did a nationwide, prospective, register-based cohort study of homeless people aged 16 years and older who were registered in the Danish Homeless Register between Jan 1, 1999, and Dec 31, 2009. We calculated the proportion of registered psychiatric disorders, overall and cause-specific standardised mortality ratio (SMR), and life expectancy. Hazard ratios (HRs) were used to assess predictors of death.

FINDINGS: 32,711 homeless people (23,040 men and 9671 women) were included in the study population. 14,381 men (62·4%) and 5632 women (58·2%) had registered psychiatric disorders, and 11,286 men (49·0%) and 3564 women (36·9%) had a substance abuse diagnosis. During the study period, 3839 men (16·7%) and 951 women (9·8%) died. The overall SMR for men was 5·6 (95% CI 5·4-5·8) and for women was 6·7 (6·2-7·1), and external causes accounted for 1161 (27·9%) of 4161 deaths for which information on the cause was available. Remaining life expectancy at age 15-24 years was 21·6 years (95% CI 21·2-22·1) and 17·4 years (16·4-18·5) lower for homeless men and women, respectively, than the general population. Registered substance abuse disorder was associated with the highest mortality risk compared with no psychiatric contact registered (adjusted HR 1·4, 95% CI 1·3-1·5 for men; 1·7, 1·4-2·1 for women).

INTERPRETATION: Health problems are extensive in the homeless shelter population and there is an urgent need for more sustained efforts to reduce the high morbidity and mortality, especially from external causes. Register data is an important resource to supplement existing knowledge on homeless people with more valid and detailed information.

FUNDING: The Danish Council for Independent Research.