Program Schedule

A Comparison of Patient Outcomes in Outpatient Parenteral Antibiotic Therapy (OPAT): Readmissions and Antibiotic Switches

Session: Oral Abstract Session: Clinical Practice Issues—OPAT in Diverse Populations
Saturday, October 11, 2014: 8:30 AM
Room: The Pennsylvania Convention Center: 109-AB

Background: β-lactam antibiotics are commonly used in outpatient parenteral antimicrobial therapy (OPAT), but data regarding outcomes of long-term therapy are limited. The purpose of this study was to compare treatment success, readmission and antibiotic switch rates in patients treated with β-lactam antibiotics as OPAT.

Methods: Retrospective review of all patients, discharged from Tufts Medical Center with cefazolin, ceftriaxone, ertapenem or oxacillin, between 2009 and 2011. Demographics, infections, antibiotics, outcomes and adverse events (AE) were recorded. Cumulative incidence of first occurrence of 30-day readmission, antibiotic switch, or treatment success for each drug was compared using competing risks analysis.  Event times were censored at 60 days.

Results: 408 patients were identified (cefazolin N=36, ceftriaxone N=109, ertapenem N=130, oxacillin N=133). Baseline demographics were similar. Treatment success rates were higher for ceftriaxone and ertapenem (cefazolin 63.9, ceftriaxone 74.9, ertapenem 75.5, oxacillin 55.1 %; chi-square p<0.001). Thirty-day all-cause readmissions were similar (cefazolin 22.2, ceftriaxone 12.4, ertapenem 18.2 and oxacillin 13.7%; p=0.39; figure 1), as were readmissions for worsening infections or AE (cefazolin 5.6, ceftriaxone 3.7, ertapenem 6.1 and oxacillin 5.3%). Antibiotic switch rates were significantly higher for oxacillin compared to others (oxacillin 21.4, cefazolin 8.3, ceftriaxone 4.1, ertapenem 1.8 %; p<0.001). Switches due to AE (figure 2) were more common than treatment failure (figure 3) (n= 31 vs. 7).  In 408 OPAT courses, 38 antibiotic switches were accomplished without readmission.  

Conclusion: OPAT with β-lactam antibiotics is effective, but antibiotic switches for adverse events were more frequent with oxacillin use. By overseeing antibiotic switches, OPAT programs may avoid AE-related readmissions, thus reducing patient morbidity and costs. Readmission avoidance should count towards the value of OPAT programs.

Fig 1. Cumulative incidence curves for all-cause 30-day readmissions

Fig 2. Cumulative incidence curves for antibiotic switches due to adverse effect

Fig 3. Cumulative incidence curves for antibiotic switches due to treatment failure



Boeun Lee, MD1, Idy Tam1, Bernard Weigel IV2, Janis Breeze, MPH3, Jessica Paulus, ScD3, Jason Nelson, MPH3 and Geneve Allison, MD, MSc, FACP1, (1)Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, MA, (2)Tufts University, Medford, MA, (3)Tufts Clinical Translational Science Institute, Tufts Medical Center, Boston, MA


B. Lee, None

I. Tam, Merck: Independent Contractor, Research grant

B. Weigel IV, Merck: Independent Contractor, Research grant

J. Breeze, None

J. Paulus, None

J. Nelson, Merck: Independent Contractor, Consulting fee

G. Allison, Coram Healthcare Infusion Company: Consultant, Consulting fee
Merck: Investigator, Research grant
Merck: Speaker's Bureau, Speaker honorarium

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