Injection drug users (IDUs) commonly use the emergency department (ED) as their primary health care access point.

We sought to characterize infectious disease clinical presentations and laboratory results of IDUs admitted to the hospital from the ED and contrast them with those of non-IDUs.

We enrolled all admitted adult patients with infectious disease–related diagnoses at a county level 1 trauma center from June 2010 to January 2011 and used a structured chart abstraction tool to record patient characteristics and clinical outcomes. We compared clinical presenting features, laboratory data, and microbiological culture results of IDUs with concomitantly enrolled non-IDUs.

Of 603 total participants, 189 were IDUs, and 414 were non-IDUs. Injection drug users had higher rates of skin and soft tissue infection admission but had similar hospital length of stay (7.5 vs 6.1 days) and mortality (2.1% vs 2.9%). Compared with non-IDUs, IDUs more commonly had hyponatremia, 38.1% vs 27.1% (mean difference, 11.4%; 95% confidence intervals [CIs], 3.4%-19.6%) and thrombocytopenia, 18.5% vs 11.0% (mean difference, 7.5%; 95% CI, 1.5%-14.2%) but less frequently had leukocytosis, 36.0% vs 52.7% (mean difference, 16.7%; 95% CI, 8.2%-24.8%). Injection drug users and non-IDUs had similar rates of positive ED-derived blood cultures, 16.5% vs 22.6% (mean difference, 6.1%; 95% CI, −13.3 to 1.7%).

When admitted from the ED for infectious disease–related diagnoses, IDUs had similar rates of fever, higher rates of hyponatremia and thrombocytopenia, and lower rates of leukocytosis than non-IDUs. Although they had similar rates of bacteremia, only IDUs were positive for methicillin-resistant Staphylococcus aureus.