Background The affliction of injecting drug use (IDU) has resulted in the emergence of a subgroup of people with a unique set of medical issues. We aimed to describe the emergency department (ED) presentations of IDUs.

Methods In a prospective observational study over a 3-month period, we identified characteristics of patients with a history of active IDU presenting to the ED.

Results From 1 January 2010 to 31 March 2010, 146 patients with a history of IDU were identified. These contributed to 222 acute presentations to the ED. Baseline characteristics revealed that patients were predominantly male, of Irish nationality, with high levels of homelessness, unemployment and lack of stable family or intimate partner relationships. 45% of presentations occurred as a result of infection (95% CI 38.5% to 51.5%). Trauma, pure toxicological issues, thromboembolic phenomena and psychiatric issues comprised the other common acute diagnoses. The burden of comorbid medical illness was substantial with high rates of hepatitis C infection (74%) and HIV infection (13.8%). Healthcare utilisation indices for this cohort are extreme on multiple measures. We found an ED attendance rate of 445 per 100 patient-years, an admission rate of 68.8 per 100 patient-years and mortality rate of 4.86 per 100 patient-years.

Conclusions Our study characterises the emergency presentations of active IDUs. We describe considerable acute and chronic medical consequences and high healthcare utilisation associated with IDU. This study is of particular relevance to any institution that provides acute medical care to this group of patients.