1796. Inappropriate Aztreonam Usage Identified as an Opportunity to Reduce Pharmaceutical Expenditures

BACKGROUND: Targeting “low-hanging fruit” is a pillar of antimicrobial stewardship (AMS). Β-lactam allergies (BLA) frequently restrict clinical decision-making and lead to utilization of alternative, less preferred antimicrobials making them an ideal AMS target. Prior studies have demonstrated that BLA are grossly over reported by patients. This study aimed to calculate the excess pharmaceutical expenditures incurred by utilization of aztreonam in patients who had previously (or subsequently) tolerated a β lactam (BL). METHODS: Retrospective chart review was performed on inpatients >18 years old at our institution who received at least one dose of aztreonam during the 2017 calendar year. Data collected included: BLA, both prior and subsequent BL classes tolerated, number of doses and days of aztreonam administered. Patients were excluded from the analysis if they did not have a documented BLA or if they received aztreonam as targeted/de-escalation therapy. Cost of aztreonam therapy was then compared with the cost of alterative BL agents based on prior and subsequently tolerated classes of BLs. Comparator agents included: pipericillin/tazobactam (penicillin), cefepime (cephalosporin) and meropenem (carbapenem). Wholesale acquisition costs were used for each agent and comparator regimens were based on our health system-wide dosing guidelines adjusted for renal function. RESULTS: One hundered thirty-two patients met inclusion criteria. Of those patients, 88/132 (66.7%) had demonstrated tolerance of a BL agent. Specifically 69/132 (52.3%) previously and 19/132 (14.4%) subsequently tolerated a β-lactam. Across the study, $40,768.84 was spent on aztreonam for patients with prior/subsequent BL tolerance. Cost for alternative therapy was estimated at $13,143.25 total; with an estimated cost difference of $27,625.59. Estimated cost difference for prior tolerance was $21,987.87 and subsequent tolerance $5,637.72. CONCLUSION: Aztreonam is an uncommon but costly antimicrobial. This study demonstrated that reduction in aztreonam utilization based on prior tolerance of β-lactam agents could lead to a meaningful reduction in pharmaceutical expenditures and serve as low-hanging fruit for an antimicrobial stewardship program. DISCLOSURES: All authors: No reported disclosures.