PIN28 A US Payer Cost-Effectiveness Analysis of Imipenem/Cilastatin/Relebactam Versus Colistin Plus Imipenem/Cilastatin in Patients with Carbapenem-Resistant Bacterial Infections

Abstract

Imipenem/cilastatin/relebactam (IMI/REL), a combination of a β-lactam antibiotic (imipenem/cilastatin) and a novel β-lactamase inhibitor (relebactam), is an efficacious and well-tolerated option for the treatment of hospitalized patients with gram-negative bacterial infection caused by carbapenem-resistant pathogens. This study evaluated the cost effectiveness of IMI/REL vs. colistin plus imipenem/cilastatin (CMS+IMI) for the treatment of infections caused by confirmed or highly suspected carbapenem-resistant pathogens. A US single payer model with a lifetime horizon comprising a decision-tree depicting initial hospitalization and a Markov model projecting long-term health and economic impact was developed. Using RESTORE-IMI 1 and US surveillance data, treatment pathways including IMI/REL or CMS+IMI among patients with confirmed or highly suspected carbapenem-resistant pathogens were simulated. Clinical outcomes (mortality and clinical response), hospital resource use, and adverse events (AE) including nephrotoxicity, were included. Subsequently, the Markov model translated hospitalization stage outcomes (mortality and cure status) to long-term consequences measured using quality-adjusted life years (QALYs). Sensitivity analyses were conducted to test model robustness. IMI/REL compared to CMS+IMI demonstrated a higher cure rate (79% vs. 52%), lower mortality (15% vs. 39%), and reduced nephrotoxicity (10% vs. 56%). Patients treated with IMI/REL gained additional 3.7 QALYs over a lifetime. Higher IMI/REL acquisition costs were offset by shorter hospital stay and lower AE-related costs; resulting in a net saving of $11,090 per patient. IMI/REL dominates CMS+IMI by being cost saving and demonstrating higher effectiveness. Sensitivity analysis showed a high likelihood (>95%) of IMI/REL being cost effective at willingness-to-pay thresholds of $100,000-$150,000 per QALY. This economic analysis, combined with established clinical and safety trial data, supports the use of IMI/REL in patients with confirmed or highly suspected carbapenem-resistant gram-negative infection. From a US Payer perspective, IMI/REL could be cost saving compared to CMS+IMI and provide a cost-effective alternative for difficult-to-treat patients with limited treatment options.