Outpatient parenteral antibiotic therapy (OPAT) and inpatient treatment strategies for emergency department patients with cellulitis: a cost analysis.

OBJECTIVES

Emergency department (ED) patients with cellulitis requiring intravenous antibiotics may be treated via outpatient parenteral antibiotic therapy (OPAT) as opposed to hospitalization. The primary objective was to compare healthcare costs for the following strategies: community intravenous antibiotics with referral to an OPAT clinic operated by infectious disease specialists ('OPAT clinic' strategy); community intravenous antibiotics with return to ED if necessary ('return to ED' strategy); and hospital admission.

METHODS

Using a hospital administrative database, we conducted a cost analysis using patient-level data of adult cellulitis patients presenting to two tertiary care EDs and were treated with intravenous antibiotics in one of three ways: OPAT clinic strategy; return to ED strategy; and hospital admission. Costs were estimated from Canada's publicly funded health system perspective. The primary outcome was the mean total cost (2015 CAD) per patient for each treatment strategy. A generalized linear model was performed to adjust for baseline characteristics, including age, sex and comorbidities.

RESULTS

A total of 808 patients met inclusion criteria: OPAT clinic strategy (N = 341); return to ED strategy (N = 228) and hospital admission (N = 239). The mean total cost of care for the treatment strategies were: OPAT clinic: $2170 (95% CI $1905-$2436); return to ED: $1493 (95 %CI $1264-$1722); and hospital admission: $10,145 (95% CI $8668-$11,622). Results from the regression analysis suggested that the OPAT clinic strategy was associated with a cost-saving of $7394 (95% CI $6154-$8633, p < 0.001) compared to hospital admission and an increased cost of $651 (95% CI $367-$935, p < 0.001) when compared to the return to ED approach.

CONCLUSIONS

This is the first Canadian study that compares the cost of different OPAT strategies for cellulitis patients. While both OPAT strategies are safe and far less costly than hospital admission, our findings suggest that a dedicated OPAT clinic for patients with cellulitis is more expensive than the return to ED strategy.