Discussion
Our study demonstrates that in a setting with a long-standing AMS
program the median duration of IV antimicrobial use was short (3 days)
and a majority of patients (57%) received timely IV-oral-switch.
Although a substantial proportion (43%) did not receive timely
IV-oral-switch, the excess IV treatment duration in these patients was
typically short (median 1.75 days). Results for general medical and
surgical patients were similar.
Numerous IV-oral-switch studies have been conducted in similar patient
groups, however many were undertaken over two decades ago when AMS
programs were in their infancy. Two recent studies examined
IV-oral-switch in patient populations similar to ours. Mouwen et
al. reviewed 138 (84 pre- and 54 post-intervention) surgical patients
to evaluate a combination of interventions to improve IV-oral-switch.
Interventions included educating physicians via a single presentation,
provision of pocket-sized cards containing a flowchart of switch
criteria plus additional information (e.g. indications for prolonged IV
therapy), and switch advice in the electronic prescribing record
[9]. The percentage of courses with timely IV-oral-switch and the
median duration of IV therapy improved significantly following
intervention (from 35.4% to 67.7%, and 5 to 3 days, respectively). Sze
and Kong reviewed 148 medical patients (72 pre-and 76-post intervention)
to evaluate printed IV-oral-switch guidelines and recommendations
attached to the medical notes of patients on the day they became
eligible for switch [10]. The proportion of IV-to-oral switches that
occurred in a timely manner significantly increased from 24.1% to
88.3% post-intervention, and delays to switching (mean days between
switch and when switch criteria were met) fell from 1.8 days to 0.2
days. The median duration of IV therapy was also significantly shorter,
falling from 4.1 to 2.8 days. In our study, the median duration of IV
therapy was shorter than the baseline (pre-intervention) findings of
these two recent studies (3.0 days versus 4.1-5.0 days), and comparable
to their post-intervention findings (3.0 days versus 2.8-3.0 days). The
percentage of courses switched in a timely manner approximated the
post-intervention results of Mouwen et al. [9] but was lower
than that of Sze and Kong [10]. A limitation of Sze and Kong’s
study, however, is that the post-intervention data collection occurred
immediately after implementation of IV-oral-switch interventions, so the
longer-term effects are unknown.
To the best of our knowledge ours is the first study to examine usual
practice within a long-standing environment of tightly regulated AMS and
IV-oral-switch guidelines. Our findings are important given
post-intervention audits in previous studies were undertaken soon after
IV-oral-switch interventions were implemented and thus may not reflect
longer-term outcomes. This is illustrated by findings from van Niekerket al. who reported that a significant improvement in timely
IV-to-oral switch after implementation of an IV-oral-switch guideline
(from 16%, 19/119 to 43%, 47/107) was not sustained three months
later, when IV-oral-switch rates had returned close to the
pre-intervention level (20.8%, 25/120) [11].
A limitation of our study was the lack of a comparison group not exposed
to our AMS program. We are unable to ascertain which element(s) of our
multi-faceted AMS approach contributed to the findings of generally
short IV treatment duration and timely IV-oral-switch. Studies have
shown improved IV-oral-switch practice with a combination of
interventions including prescriber education, printed guidelines
inserted in patients’ case notes, reminder stickers on medication
charts, prospective audit and feedback and electronic alerts [3],
[5], [9, 10, 11, 12, 13]. Unfortunately, few IV-oral-switch
studies have described what AMS programs were already in place prior to
the IV-oral-switch intervention, making comparisons difficult. Given
that the two most commonly prescribed IV antimicrobials in our study
(ceftriaxone and amoxicillin-clavulanate) were agents requiring prior
approval before prescribing, it’s likely our preauthorization system
(with time-limited approvals) helped ensure IV-oral-switch was
considered by day 2–3 of therapy. Preauthorization has been shown to
optimise empiric choices, reduce antibiotic use and costs, increase
rates of susceptible pathogens and decrease rates ofClostridioides difficile infection [14], [15]. However,
to the best of our knowledge no studies have specifically examined
preauthorization as a strategy to improve other AMS targets such as
timing of IV-oral-switch.
An interesting finding of our study concerns the total duration (IV plus
oral) of antimicrobial therapy. There is growing evidence that shorter
therapy durations are as effective as longer durations for common
infections [16]. We found that 45% of patients received an
excessive total duration of therapy, and this may underestimate the
magnitude of this issue. For example, at the time of our study national
antimicrobial prescribing guidelines recommend seven days of treatment
for community-acquired pneumonia (CAP) [8]. However, these
guidelines recently changed to incorporate a shorter duration of five
days for mild to moderately severe CAP based on recent evidence [17,
18]. There were fifteen (14.0%) patients with CAP in our cohort that
received antibiotic treatment for a median of seven days. Longer
durations of therapy are associated with increased risk of antimicrobial
resistance, secondary infections and greater costs [19, 20, 21].
Therefore, future AMS activities should incorporate the most recent
evidence for treatment duration to further optimise therapy and reduce
associated hazards.
In summary, the practice of IV-oral-switch at our hospital was generally
concordant with guidelines, suggesting that a tightly regulated AMS
program with preauthorisation for target IV antimicrobials may lead to
sustained good IV-oral-switch practice. Total duration of therapy was
identified as an AMS target to improve antimicrobial prescribing and
patient safety.
- Acknowledgement: We would like to acknowledge Associate
Professor Jason Trubiano for his contribution to this manuscript.
- Conflict of interest: None to declare
- Funding: This research did not receive any specific grant
from funding agencies in the public, commercial, or not-for-profit
sectors.
- Data availability statement: The data that support the
findings of this study are available from the corresponding author
upon reasonable request.
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Table caption: Table 1: Characteristics of patients and antimicrobial use