Formulary Management and Antimicrobial Stewardship: a 7-year Evaluation at an Integrated Health-System

BACKGROUND: The antimicrobial formulary is a key tool in antimicrobial stewardship (ASP). Agents added to formulary typically are those that have been formally reviewed and determined to have a place in therapy in a given facility. Non-formulary (NF) agents generally are those that have not been requested, or were deemed not optimal based on spectrum, formulation, or cost. We evaluated NF antimicrobial orders to identify possible gaps in optimal use and process. METHODS: IRB-exempt ecological evaluation of NF antimicrobial use in multi-site healthcare system. Anonymous data collected: NF antimicrobial agents ordered between 2010–2017. Drug use characteristics: class, duration, availability of formulary alternatives, and time since FDA approval. Descriptive statistics were used to characterize NF use. Additional formulary processes evaluated: requests, reviews, and decisions. RESULTS: 2041 NF antimicrobial were ordered for 44 different agents, representing < 0.01% of all medication orders. Drug class: Antibacterials (65%), antivirals (21%), antifungals (12%). Most common agents: levofloxacin (25%), cefpodoxime (17%), anidulafungin (10%), nitrofurantoin macrocrystal (10%), ledipasvir-sofosbuvir (6%). Of 421 orders for antivirals, indication was: 53% for hepatitis C. Thirty-seven percent of orders were for 1 day only, suggesting continued use outpatient. 3% of orders had an extended duration of therapy > 14 days. 185 orders were placed for new drugs (within 12 months of FDA-approval), 73% were for HIV agents. 11 of 44 NF agents were subsequently added to the formulary. During the study period, 17 antimicrobial were requested for either inpatient or outpatient formulary addition; all were approved with use criteria or infectious diseases restriction. Of 16 antimicrobial agents FDA-approved during the study period, 6 were requested and added to the inpatient formulary. Fifty-two percent of agents had alternatives in the same class on formulary at the time of use. Potential safety problems identified: dose and duration of therapy. CONCLUSION: Formulary structure provides systematic approach for drug selection, dose, and duration. Monitoring NF antimicrobials use can aid in identification of ASP priorities, with implications for medication safety and patient outcomes. DISCLOSURES: S. L. Davis, Allergan: Grant Investigator and Scientific Advisor, Consulting fee and Research grant. Merck: Grant Investigator and Scientific Advisor, Consulting fee and Research grant.