Predicting observation unit treatment failures in patients with skin and soft tissue infections

BACKGROUND: Skin and soft tissue infections are a common admission diagnosis to emergency department (ED) observation units (OU). Little is known about which patients fail OU treatment. AIMS: This study evaluates clinical factors of skin or soft tissue infections associated with further inpatient treatment after OU treatment failure. METHODS: A structured retrospective cohort study of consecutive adults treated for abscess or cellulitis in our OU from April 2005 to February 2006 was performed. Records were identified using ICD-9 codes and were abstracted by two trained abstractors using a structured data collection form. Significant variables on univariate analysis P < 0.1 were entered into a multivariate logistic regression. RESULTS: A total of 183 patient charts were reviewed. Four patients with a non-infectious diagnosis were excluded, leaving 179 patients. The median age was 41 (interquartile range: 20–74). Following observation treatment, 38% of patients required admission. The following variables were evaluated for association with failure to discharge home: intravenous drug use, gender, a positive community-acquired methicillin-resistant Staphylococcus aureus culture, age, presence of medical insurance, drainage of an abscess in the ED, diabetes and a white blood cell count (WBC) greater than 15,000. Following multivariate analysis only female gender odds ratio (OR) 2.33 [95% confidence interval (CI): 1.06–5.15] and WBC greater than 15,000 OR 4.06 (95% CI: 1.53–10.74) were significantly associated with failure to discharge. CONCLUSIONS: Among OU patients treated for skin and soft tissue infections, women were twice as likely to require hospitalization and patients with a WBC > 15,000 on presentation to the ED, regardless of gender, were 4 times more likely to require hospitalization.