Impact of an Antimicrobial Stewardship Program in a Safety-Net Hospital with Low Baseline Antibiotic Use

Background:   Antimicrobial stewardship programs can reduce antibiotic use and costs in both academic and community hospitals; however, their impact in safety-net hospitals and those with already low antibiotic use has not been described.  We evaluated the effects of a stewardship program implemented in a safety-net hospital with low baseline antibiotic use.

Methods: Denver Health is an academic public safety-net hospital.  Antibiotic use was nearly the lowest among University Health Consortium hospitals prior to implementation of a formal stewardship program in July 2008.  We performed a before-after study to evaluate outcomes during a 2-year baseline period immediately prior to the program (7/1/06 – 6/30/08) and the 4.5 years after its inception (7/1/08 – 12/31/12).  The primary outcome was the change in total antibiotic use between the two periods.  Secondary outcomes were changes in use of antibiotics active against Pseudomonas aeruginosa, rate of hospital-onset Clostridium difficile infection (CDI), length of stay, in-hospital mortality, and 30-day readmission rates for patients who received an antibiotic, and antibiotic-acquisition costs. 

Results: Between the baseline and stewardship periods, mean total antibiotic use decreased 7% from 604 to 563 days of therapy (DOT) per 1000 patient-days (PD) (p<.001).  Mean use of anti-pseudomonal agents decreased 20% from 187 to 150 DOT/1000PD (p<.001), including significant reductions in imipenem (22 vs. 5 DOT/1000PD, p<.001), fluoroquinolones (61 vs. 45 DOT/1000PD, p<.001), and aminoglycosides (26 vs. 19 DOT/1000PD, p = .002).  The rate of hospital-onset CDI remained stable between periods.  For patients who received an antibiotic, mean length of stay decreased (7.0 vs. 6.4 days, p<.001); in-hospital mortality (2.2 vs. 2.1%, p = .36) and 30-day readmission rates (13.9 vs. 14.5, p = .16) were similar.  Antibiotic acquisition costs decreased 19% from $10,299 to $8,360/1000PD (p = .008) 

Conclusion: Implementation of a stewardship program in a safety-net hospital with low baseline antibiotic use was associated with reductions in total and broad-spectrum antibiotic use and cost savings.  This work adds to the literature demonstrating the success of stewardship programs in a variety of hospital settings and suggests that there is the potential for benefit in hospitals with relatively low antibiotic use.