OBJECTIVES: Severe abdominal sepsis and septic shock (SAS-SS) are common problems in intensive care units (ICU), and carry high mortality. This study assessed the cost-effectiveness of Polymyxin B immobilized fiber column (PMX) plus conventional therapy (CT) (PMX-CT) versus CT alone, for SAS-SS, in the perspective of the Italian NHS (hospital). METHODS: This study was a retrospective cost-effectiveness analysis (CEA) with clinical efficacy and consumption of resources collected alongside an RCT (Cruz et al. JAMA 2009). 64 SAS-SS patients were enrolled following emergency surgery for intra-abdominal infection in 10 tertiary care ICUs, from 12/2004 to12/2007. Costs included: hospital days, ICU days; catecholamine treatment days; renal replacement therapy (RRT) days; mechanical ventilation treatment (MVT) days; use of PMX device. Resources were valued using published tariffs and market values. All-cause hospital mortality was extrapolated to survival (expected life-years per patient/arm): for each survivor average life expectancy (in years) by age and sex was retrieved from National Life Tables; for deceased patients, only the number of survival days as reported in the CRF, was retained. Per patient survival was then weighed using a predicted death rate based on individual Apache II scores, to account for disease severity. Univariate sensitivity analyses on costs and outcomes and 2000 Bootstrap simulations were run to test CEA’s results. RESULTS: Based on the expected number of survival years (PMX-CT 8.24/patient, CT 4.69/patient), the mean difference in survival yielded an expected increase of 3.55LYG/patient for PMX-CT, at the additional cost of €13,411/patient with a mean ICER of €3,774/LYG and a median ICER of €2,776/LYG.  Results of the base-case CEA were confirmed by all sensitivity analyses with ICER values always well below commonly accepted value thresholds.CONCLUSIONS: PMX-CT vs. CT is a cost-effective intervention for treatment of severe abdominal sepsis and septic shock and should be considered for use in the Italian NHS’ hospital setting.