November 02, 2012
ABSTRACT
Background:
Use of patient-specific culture data to optimize empiric therapy is a cornerstone of rational hospital antibiotic use. The frequency with which cultures are obtained and therapy tailored to results is unknown.
Methods:
We performed a cross-sectional study using retrospective chart review of 1,200 adult inpatients, hospitalized >24hrs, with >=1 active antibiotic order. Patients were enrolled for 4 index dates at quarterly intervals during a 1-year study period (9/2009-10/2010). Infectious disease (ID) specialists recorded demographics, comorbidities, antibiotic therapy, imaging studies and culture results in a 17d window, and categorized changes to therapy. No change was defined as the continuation of the course as initially ordered; de-escalation was a change resulting in narrower coverage; escalation was a switch to/addition of an antibiotic resulting in broader coverage. A Cox proportional hazard model stratified by infection site was used to model time to de-escalation. Patients receiving <=1 antibiotic prescription and/or exclusively prophylactic courses were excluded from the analysis.
Results:
Of 1,200 charts that were reviewed, 631 patients(52.6%) were included in the analysis. Of these, 288 (45.7%) were not changed, 192 (30.4%) were de-escalated and 151 (24%) were escalated. De-escalated prescriptions included 18 fully discontinued courses (2.85%), 61 de-escalations without culture results (9.7%), and 113 de-escalations based on cultures (17.9%). The no-change category included 250 continued as initially ordered (39.6%) and 38 switches to equivalent antibiotics (6%). De-escalation was most common for urinary infections (46%). Patients that received fewer prescriptions, were started on broad-spectrum antibiotics, had elevated WBC at start of course, shorter pre-therapy LOS had higher probability of de-escalation. However, positive culture and imaging study had no significant effect.
Conclusion:
Although patients with suspected infections were frequently cultured, clinicians changed antibiotics in less than half of patients receiving multiple therapies. Availability of positive culture and/or imaging study suggestive of infection did not have a significant impact on de-escalation probability.