The audit aims to identify the adherence to local guidelines for appropriate usage of high cost antifungals including therapeutic drug monitoring (TDM)
The data sample was identified using a medication trace (through the pharmacy dispensing system JAC®) of the 4 High Cost antifungals on the Hospital formulary. Patients who received any formulation of AmBisome®, Caspofungin, Voriconazole & Posaconazole were identified over the preceding two years (April 2014- April 2016).
Healthcare notes of the identified patients were then accessed for the audit data alongside the hospital’s pathology reporting system WinPath®. Parameters such as drug prescribing, endorsements, microbiology discussion documentation, TDM, documented dose banding for IV Voriconazole and AmBisome® and Child Pugh (CP) score in case of Caspofungin were assessed.
72 patient notes with a total 130 prescriptions were reviewed. The average compliance to the guidelines for choice (indication) or on Microbiology advice was 91.2% and is just short of the target 95%.
Compliance to the guidelines was 100% for the prescribing of dose, route & frequency but only 70% compliance with the drug form, especially for Voriconazole as oral formulation exist in liquid and tablet form with differing bioavailability.
Percentage compliance for endorsement for indication was low for Posaconazole (50%) and the percentage compliance for endorsement duration was low for AmBisome® (50%).
TDM was only necessary with Voriconazole, however 86% of all prescriptions for Voriconazole did not have any documented results.
All three patients with liver derangement, who were prescribed Caspofungin had documented CP score on the drug chart (100% compliance)
Public Health England report1 in 2015 reported the overall rate of candidaemia in England, Wales and Northern Ireland of 2.8 per 100000 in 2014. Patients with invasive fungal infections (IFI) have longer durations of hospital stay due to need for long periods of expensive inpatient therapy. Patients are also likely to suffer serious complications of the infections and toxicity issues associated with treatments. Despite costs associated with the use of these agents the quality of prescribing remains poor2.
Education of prescribers regarding dose banding and TDM for relevant antifungals along with need to review lack of guidelines for certain specialities is recommended. Pharmacist need to challenge prescriptions where dosing is not in line with patient weight or dose banding tables (where relevant). Compared to previous audit in 2010 drug chart endorsements have improved however clear documentation and close liaison with microbiology for IFI are essential to help doctors prescribe safely and reduce any side effects.
Referemces : 1. Public Health England report 2015, Infection Report, Surveillance of candidaemia in England, Wales and Northern Ireland: 2014, Volume 9 Number 33 Published on: 18 September 2015.
2. Micallef C, Aliyu SH, Santos R, et al. Introduction of an Antifungal stewardship programme targeting high cost antifungals at a tertiary hospital in Cambridge, England. J. Antimicrob. Chemother. (2015).