Objectives To describe patterns of service use and to predict risk factors for re-presentation to a metropolitan emergency department (ED) among people who are homeless.

Methods A retrospective cohort analysis was undertaken over a 24-month period from a principal referral hospital in Melbourne, Australia. All ED visits relating to people classified as homeless were included. A predictive model for risk of re-presentation was developed using logistic regression with random effects. Rates of re-presentation, defined as the total number of visits to the same ED within 28 days of discharge, were measured.

Results The study period was 1 January 2003 to 31 December 2004. The re-presentation rate for homeless people was 47.8% (3199/6689) of ED visits and 45.5% (725/1595) of the patients. The final predictive model included risk factors, which incorporated both hospital and community service use. Those characteristics that resulted in significantly increased odds of re-presentation were leaving hospital at own risk (OR 1.31; 95% CI 1.10 to 1.56), treatment in another hospital (OR 1.45, 95% CI 1.23 to 1.72) and being in receipt of community-based case management (OR 1.31, 95% CI 1.11 to 1.54) or pension (OR 1.34, 95% CI 1.12 to 1.62).

Conclusions The predictive model identified nine risk factors of re-presentation to the ED for people who are homeless. Early identification of these factors among homeless people may alert clinicians to the complexity of issues influencing an individual ED visit. This information can be used at admission and discharge by ensuring that homeless people have access to services commensurate with their health needs. Improved linkage between community and hospital services must be underscored by the capacity to provide safe and secure housing.