Real-World Effectiveness and Cost-Effectiveness of Ceftazidime–Avibactam versus Colistin–Meropenem for ICU-Acquired MDR Gram-Negative Infections in Liver Transplant Recipients

<title>Abstract</title> <p>Background Novel β-lactam/β-lactamase inhibitor combinations have expanded treatment options for carbapenem-resistant Gram-negative infections; however, comparative real-world evidence in critically ill liver transplant recipients remains limited. We compared the clinical effectiveness and cost-effectiveness of ceftazidime–avibactam (CAZ/AVI) with colistin–meropenem for intensive care unit (ICU)-acquired multidrug-resistant (MDR) Gram-negative infections in adult liver transplant recipients. Materials and Methods In this retrospective comparative cohort study, 190 adult liver transplant recipients treated between October 2021 and April 2025 received definitive therapy with either CAZ/AVI monotherapy (n = 100) or colistin–meropenem combination therapy (n = 90). The primary outcome was clinical response. Secondary outcomes included microbiological eradication, sepsis-related mortality, 30-day all-cause in-hospital mortality, ICU and hospital length of stay, and pharmacoeconomic outcomes. Cost-effectiveness was assessed using incremental cost-effectiveness ratios (ICERs), non-parametric bootstrap resampling, cost-effectiveness planes, and cost-effectiveness acceptability curves. Results Clinical response was significantly higher with CAZ/AVI than with colistin–meropenem (87.5% vs 57.6%, p &lt; 0.001). CAZ/AVI also achieved higher microbiological eradication (95.8% vs 72.9%, p &lt; 0.001) and substantially lower sepsis-related mortality (11.1% vs 42.4%, p &lt; 0.001), whereas 30-day all-cause in-hospital mortality did not differ significantly between groups (p = 0.377). Although antimicrobial acquisition costs were higher with CAZ/AVI, pharmacoeconomic analyses demonstrated favorable cost-effectiveness, with an ICER of 54,442.13 TL per additional clinical success, supported by bootstrap and acceptability analyses. Conclusions CAZ/AVI was associated with superior clinical response, greater microbiological eradication, lower sepsis-related mortality, and favorable cost-effectiveness compared with colistin–meropenem. These findings support CAZ/AVI as an effective definitive treatment option for critically ill liver transplant recipients with ICU-acquired MDR Gram-negative infections.</p>