Effect and economic impact of a Standardized
Orders for Antimicrobial Prophylaxis program
Luciana Frighetto, Carlo A Marra, H Grant Stiver, Elizabeth
A Bryce and Peter J Jewesson
University of British Columbia, Vancouver, Canada
The use of peri-operative antibiotic treatment has been shown
to reduce the rates of surgical wound infections (1). At the same time, it is recognized that inappropriate use
of antibiotics may foster emergence of antibiotic-resistant pathogens and consequent worse clinical outcomes (2,3).
While antibiotic prophylaxis for surgery is widely used, data suggest that the process of antibiotic prophylaxis
(specifics of the protocol and its implementation) and infection control (i.e., surgical technique and hospital
infection-control measures) need to be optimized (3-5). Improvements could help to reduce both surgery-related
infections and the rise and spread of antibiotic-resistant pathogens.
Recommendations for antibiotic choice for prophylactic regimens are based on the pathogens most commonly isolated
from wound infections following each of the various types of surgical procedures (1,6). For clean wounds, especially
those involved in implantation of prostheses (e.g., cardiac, orthopedic, vascular), infections are commonly due
to skin flora including Staphylococcus aureus and Staphylococcus
epidermidis. For these procedures first generation cephalosporins
are often recommended. For various abdominal and pelvic surgeries, coverage for coliforms and anaerobes is warranted,
often through the use of second or third generation cephalosporins. Clearly, antibiotic choices for the various
surgical procedures may change as the prevalence of resistant strains of these species to the commonly used antibiotics
In addition to the choice of antibiotic, there are several additional aspects of the antibiotic regimen and additional
steps in the process of surgical wound prophylaxis which need to be optimized to maximally reduce rates of post-surgical
infection. Clinical trials have demonstrated that timely administration of prophylactic antimicrobials can reduce
post-operative morbidity, shorten hospitalization and reduce overall health care costs (4,7-9). Most authorities
recommend the intravenous administration of a suitable antimicrobial immediately before the time of the surgical
incision (10-13). The landmark study by Classen et al (4) revealed that the timing of pre-operative antimicrobial
administration does not always match current recommendations. More importantly, these investigators confirmed a
direct relationship between antimicrobial timing and the risk of development of surgical wound infection (SWI).
These findings have been corroborated by others (5,14-16).
To our knowledge, there have been no published reports describing an interdisciplinary approach to optimizing timing
of pre-operative antimicrobial doses in which both the impact on practice patterns and the economic implications
have been evaluated. We therefore undertook a study to assess the effect and economic impact of an interdisciplinary
approach to standardizing the timing of pre-operative antimicrobial prophylaxis from the perspective of a major
teaching, university-affiliated hospital.
Vancouver General Hospital is an 1100-bed tertiary care, university-affiliated institution that completes approximately
12,500 surgical procedures per annum. At the time of the current study, there were no hospital-wide protocols to
ensure optimal timing of administration of pre-operative antimicrobial doses and a review revealed inconsistent
practice similar to that described by Classen et al (4). An in- terdisciplinary 2-stage intervention was implemented.
A policy was developed whereby pre-operative parenteral prophylactic antimicrobials would be administered by nurses
or anesthetists in the preoperative/operating room (OR) areas only. An article containing information about the
general principles of surgical antimicrobial prophylaxis, rationale and endorsement for the initiative, and a description
of the policy for the timing of administration of pre-operative antimicrobials introducing this standardized orders
for antimicrobial prophylaxis (SOAP) initiative was written and published in an internal newsletter. During the
second stage of the intervention, pharmacists were authorized to modify non-compliant prescriptions to read ìto
be administered in the pre-operative area/OR immediately prior to skin incision if required.
A pre/post study design was employed to assess the impact of the intervention. For each prophylactic course, the
timing of the pre-operative dose administration was classified relative to incision time as early (>2 hours
prior to incision), on time (0-2 hours prior), delayed (0-3 hours after) or late (>3 hours after). In addition,
the location and staff member who administered the prophylactic antimicrobial were determined for each phase. A
decision analysis model was used to assess the costs and outcomes associated with each of the two competing strategies
of conditions without SOAP and with SOAP from the institutional perspective. The probabilities for the development
of SWI used in the model were derived from the published literature (1). The marginal treatment costs for SWI were
obtained from retrospective reviews of the health records of SWI cases.
Patient demographics, prophylactic antimicrobials, and surgical service included in the antimicrobial administration
were similar between the two phases. In the pre-intervention phase (without SOAP), 68% of prophylactic courses
were administered on time, 22% were early while the balance were delayed or late. The incidence of on time prophylaxis
increased to 97% during the post-intervention phase (p=0.001). Operating room staff involvement in prophylactic
anti- microbial administration increased from 57% (without SOAP) to 92% (SOAP) (p=0.001); therefore, administration
of antimicrobials in the OR area increased from 58% to 98% (p=0.001).
The SOAP strategy resulted in an estimated annual reduction of SWI cases, from 91 cases to 40 cases resulting in
an avoidance of 153 days of hospitalization, and $99,807 CAN. Since this strategy incurred $9100 CAN for implementation
and maintenance, the actual cost avoidance was $90,707 CAN which translates into $1,779 CAN saved per inpatient
Study of the practices of antibiotic utilization for surgical infection prophylaxis highlight the need for optimal
antibiotic practice-guideline development and implementation, and for the adherence to hospital infection control
procedures. Research continues to evaluate different antibiotic regimens (e.g., shortening treatment duration;
17) and several approaches to implementing currently accepted practices are being explored (e.g., the use of computer-assisted
decision support programs;16). The SOAP strategy appears to provide an effective, low-cost, interdisciplinary approach
to optimizing timing of pre-operative antimicrobial doses in which both the impact on practice patterns and the
economic implications have been evaluated. While the focus of this program was the timing of the initial antibiotic
dose administration, the success of the SOAP program and enthusiasm for this approach among various members of
the hospital staff (including surgical and infectious disease clinicians) provides an opportunity to further expand
this model to address other aspects of antibiotic prophylaxis regimens (type, amount, duration of treatment, route)
to promote more effective wound infection prophylaxis and, through more appropriate antibiotic usage, to try to
reduce the prevalence of antibiotic-resistant pathogens.
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