Impact of an Antibiotic Stewardship Program (ASP) on Length of Stay (LOS)

Background: Historically, ASP’s most often have been promoted as a means to reduce the propagation of antimicrobial resistance and reduce costs.  Little has been done to document the direct impact of ASP’s on patient outcomes.

Objective: Employing an ASP in a community-based, 300 bed acute care hospital, we prospectively determined if a ASP could have a impact on reducing LOS.

Methods: Using a team that included an infectious disease (ID) pharmacist and ID physician, the ASP was administered from October 2005 to March 2007 (18 months). Antibiotic restriction was not utilized. ASP defined interventions included daily review of culture data and individual patient antibiotic profiles. Written or verbal consultations were provided to the physician including antibiotic change when deemed appropriate. LOS was captured in all patients who received an antibiotic for at least 72 hours and compared to the LOS prior to the ASP initiation. Statistical analysis of LOS was reported in two-day intervals and analyzed with a T-Test and regression analysis (GLM procedure).

Results: 11,841 patients prior to ASP initiation (4 years) and 4678 patients after the ASP initiation were reported. The average age of patients after ASP implementation was 2 years younger than before the program was started. 90% of all recommendations were accepted by the physician. Measures of Severity of Illness, Case Mix Index and APR-DRG, were stable over the study period. Average LOS was reduced by one-half day (11.0 vs. 10.5, p<0.017), maximum LOS reduced by 5.2 days (36.2 vs. 31.0, p=0.0008), and the standard deviation of LOS was reduced by 0.92 days (9.4 vs. 8.5, p=0.027)  Minimum LOS did not change. (p=0.11) ANOVA, with age as a covariate demonstrated that age had no effect on LOS. Hospital antimicrobial acquisition costs were reduced 30%.

Conclusions: ASP’s can improve reduce LOS in ID patients.