631. Economic Analysis of Imipenem/Cilastatin/Relebactam Compared to Piperacillin/Tazobactam for Treating Hospital-Acquired and Ventilator-Associated Bacterial Pneumonia

Abstract Background Hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP) is associated with high rates of morbidity and mortality; this is often worse among patients who experience a delay in receiving appropriate therapy. Initial treatment choice and early adjustment occurs prior to pathogen susceptibility results and may be based on suspicion of a resistant infection and/or clinical deterioration. This study assesses the cost effectiveness of Imipenem/cilastatin/relebactam (IMI/REL) in an early adjustment prescribing scenario compared to PIP/TAZ for patients with high risk of resistant infection from a US perspective. Methods Although early adjustment data was not directly available, pathogen susceptibility data derived from 2017-19 Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program was applied to estimate patients who may have clinical worsening, likely due to a resistant infection. The efficacy and safety data for IMI/REL and PIP/TAZ were informed by the modified intent-to-treat population of a phase III trial (RESTORE-IMI 2). Our analysis comprised a decision tree (reflecting hospitalization period) followed by a yearly Markov model (capturing lifetime impact). The decision tree captured short-term outcomes (clinical cure, all-cause mortality, and hospital resource use). The Markov model translated short term outcomes into quality-adjusted life years (QALYs). Results were expressed as an incremental cost-effectiveness ratio (ICER). Sensitivity analyses were conducted to test the robustness of model results. Results Compared with PIP/TAZ, IMI/REL in the early adjustment setting was associated with increased costs (&10,087 per patient) but a higher cure (+7%) and lower mortality (-3%) rate. The resulting ICER (&12,173/QALY) falls well below typical US willingness to pay thresholds. Model drivers were the SMART-based susceptibility profiles and RESTORE-IMI 2 response and mortality rates. Conclusion Our results suggest that IMI/REL, used as an early adjustment option, could be considered cost effective for patients with worsening HABP/VABP in a US setting, when compared against PIP/TAZ. Disclosures Jaesh Naik, MSc, BresMed Health Solutions (Employee) Lewis Ralph, MSc, Bresmed (Employee) Ryan J. Dillon, MSc, Merck & Co. Inc., (Employee, Shareholder) Joe Yang, Ph.D., Merck & Co (Employee)