ECONOMIC EVALUATION of PROPHYLACTIC IMMUNOGLOBULIN VERSUS PROPHYLACTIC ANTIBIOTICS in HEMATOLOGICAL MALIGNANCIES: RESULTS from the RATIONAL FEASIBILITY TRIAL.

Abstract

Background: Patients with hematological malignancies are at high risk of infections due to their disease and associated treatments. The use of immunoglobulin (Ig) to prevent infections is increasing in this population, but its cost-effectiveness is unknown. Aim(s): The aim of this trial-based economic evaluation was to estimate the 12-month cost-effectiveness of prophylactic Ig versus prophylactic antibiotics in patients with acquired hypogammaglobulinemia secondary to hematological malignancies Methods: Our economic evaluation used individual patient data from the RATIONAL feasibility trial, which randomized 63 adults with chronic lymphocytic leukemia, multiple myeloma, or lymphoma to prophylactic Ig or prophylactic antibiotics. Two analyses were conducted over the 12-month trial period and from the perspective of the Australian healthcare system: 1) Cost-utility analysis (CUA) to assess the incremental cost per quality-adjusted life-year (QALY) gained, using data collected with the EQ-5D-5L instrument; 2) Cost-effectiveness analysis (CEA) to assess the incremental cost per serious infection prevented (grade >=3) and per infection (any grade) prevented. A probabilistic sensitivity analysis with 1,000 iterations of incremental costs and QALY pairs was performed to explore the uncertainty around the CUA results. Result(s): The total cost per patient was significantly higher in the Ig arm than in the antibiotic arm (mean difference AU$29,140; 95%CI $15,941, $42,340). There were non-significant differences in health outcomes between treatment arms. Patients treated with Ig had fewer QALYs than those given antibiotics (mean difference-0.072; 95%CI-0.167, 0.023), fewer serious infections (mean difference-0.26; 95% CI-0.74, 0.21), but more overall infections (mean difference 0.76; 95%CI-0.33, 1.86). The incremental cost-effectiveness ratio (ICER) in the CUA indicated Ig was dominated by antibiotics (i.e., Ig was more costly and associated with fewer QALYs). In the CEA, the ICER for Ig versus antibiotics was AU$111,262 per serious infection prevented, and Ig was dominated by antibiotic treatment when all infections were included (i.e., Ig was more costly and associated with more infections). The probabilistic sensitivity analysis (Figure 1) showed the majority of ICER pairs were in the <<north-western>> quadrant, above the AU$50,000 willingness to pay threshold, indicating Ig was not costeffective compared to antibiotics. (Figure present) Summary/Conclusion: These results indicate that, on average and for this group of patients with hematological malignancies recruited to the RATIONAL feasibility trial, Ig prophylactic treatment was not cost-effective compared to prophylactic antibiotics during the 12 months follow-up period. A very large increase in QALYs may be needed for Ig to become cost-effective due to its high cost. Nevertheless, given the small sample size and non-significant differences in health outcomes, further research is needed in a larger population and considering longer-term outcomes. A follow-on trial is currently open for recruitment and will provide an opportunity to confirm these findings (ACTRN12622000359730).