Methods
A retrospective review of general medical and surgical patients on four wards prescribed one or more IV antimicrobials for ≥48 hours was undertaken over two months (29 October to 21 December 2018). Patients were identified via electronic prescribing records and excluded if: antimicrobial(s) were prescribed for a non-infective condition; infection required a prolonged course of IV treatment (e.g. endocarditis); patient unable to take oral therapy or no oral option available; patient transferred to another ward, hospital or outpatient parenteral antimicrobial therapy; or patient died during IV antimicrobial therapy.
An IV antimicrobial course was defined as receiving one or more IV antimicrobials. If the timing of IV-oral-switch was deemed inappropriate for one agent in a combination, the entire course was considered inappropriate.
Data was collected from patients’ electronic medical records and included: variables listed in the IV-oral-switch guideline (Supplement), infection type, antimicrobial(s) prescribed, antimicrobial allergy history, microbiology test results and total duration of therapy (IV plus oral). The timing of IV-oral-switch, choice of oral antimicrobial(s), and total duration of therapy were assessed by an ID pharmacist and ID physician against local and national antimicrobial prescribing guidelines [8].
The primary outcome was the proportion of patients switched to oral antimicrobial(s) within 24 hours of meeting switch criteria. Secondary outcomes were: median number of days of IV antimicrobial(s) before IV-oral-switch, time delay to switch (difference in days between the actual switch date and 24 hours after meeting switch criteria), appropriateness of choice of oral alternative(s), and total duration of antimicrobial therapy (IV plus oral). All outcomes were compared across medical and surgical patients to identify differences in IV-oral-switch and total duration of therapy. Statistical analyses were performed using Microsoft Excel (2016) and Stata version 15. Ethical approval was obtained from the Austin Health Human Research Ethics Committee (LNR/18/Austin/369) and Monash University Human Research Ethics Committee (18733).