Eligibility criteria
This was a single center retrospective review approved by the University of Kentucky Institutional Review Board (IRB). All patients aged one month or older with a diagnosis of CF who received IV tobramycin for treatment of a PsA APE during an admission to the University of Kentucky Healthcare System between August 1, 2015 and August 31, 2019 were evaluated for inclusion. Patients were excluded if they had no growth of PsA on sputum culture(s) prior to or during admission, if they had chronic kidney disease (CKD) prior to receiving the first dose of IV tobramycin, or if two post-dose drug levels were not obtained during admission to calculate patient-specific pharmacokinetic parameters. Further, patients were excluded from primary outcome analysis if two drug levels were not obtained following a dose adjustment of greater than 20% or following adjustment of the dosing interval secondary to fluctuating renal function.
Pharmacokinetic parameters were collected following any dose adjustment of IV tobramycin, and only the parameters collected from the final dose (i.e. based on clinical judgement, did not warrant further dose adjustment) were analyzed in the primary outcome analysis. Within the adult cohort, if a patient had >4 encounters over the four-year study period, only the first four encounters were collected and subsequently analyzed.