Cost-Effectiveness Analysis of Polymyxin-B Immobilized Fiber Column and Conventional Medical Therapy in the Management of Abdominal Septic Shock in Italy

Abstract

Introduction: Severe abdominal sepsis and septic shock are common problems in intensive care units (ICUs), and carry high mortality. The purpose of this economic analysis was to determine the cost-effectiveness of polymyxin B immobilized fiber column (PMX-F) plus conventional therapy (CT) (PMX-F-CT) versus CT alone for patients with severe sepsis/septic shock of abdominal origin, in the perspective of the Italian hospital. Methods: This was a retrospective cost-effectiveness analysis (CEA) based on data of clinical efficacy and consumption of resources collected alongside an Italian randomized clinical trial. 64 patients were enrolled following emergency surgery for intra-abdominal infection in 10 tertiary care ICUs from December 2004 to December 2007. Direct medical costs analyzed in the study included the consumption of hospital days, ICU days, catecholamine treatment days, renal replacement therapy days, mechanical ventilation treatment days, and the use of the PMX-F device. Resources were valued using published 2010 tariffs and market values. All-cause hospital mortality was extrapolated to survival as expected life years (LY) per patient/arm: for each survivor, average age-gender-related years of life expectancy were retrieved from national life tables; for deceased patients, only the number of CRF reported survival days was retained. Baseline expected years of survival were weighed by the severity of sepsis, according to individual Acute Physiology and Chronic Health Evaluation (Apache) II scores, showing that age/disease severity were comparable in the two groups before treatment initiation. Life expectancy per patient in each treatment group was thus calculated as the combination of life expectancy from Italian National Statistics Institute life tables and intra-hospital mortality detected in the Early Use of Polymyxin B Hemoperfusion in Abdominal Septic Shock (EUPHAS) study. After all costs and 3% discounted survival years were calculated per patient per treatment arm, the incremental CEA was run to obtain the incremental cost-effectiveness ratio (ICER). Univariate sensitivity analyses and 2,000 bootstrap replications were run to test the robustness of the study results. Results: Based on the expected survival years (mean discounted PMX-F-CT 9.37 LY/patient, CT 4.92 LY/patient; difference for PMX-F-CT 4.45 LY/patient; mean undiscounted PMX-F-CT 13.92 LY/patient, CT 7.19 LY/patient; difference +6.73 LY/patient), and the expected mean cost (PMX-F-CT mean 59,922 EUR/patient, CT mean 42,712 EUR/patient; difference for PMX-F-CT 17,211 EUR/patient), the mean ICER for PMX- F-CT resulted in 3,864 EUR/life year gained (LYG; ICER 2,558/undiscounted LYG). Results of the base-case CEA were confirmed by all sensitivity analyses, with ICER values always well below commonly accepted value thresholds. Conclusion: PMX-F-CT versus CT is a cost-effective intervention for treatment of severe sepsis/septic shock of abdominal origin and could be considered for use in the Italian National Health System hospital setting.