OBJECTIVES : To assess the cost effectiveness of belimumab IV or belimumab SC added to standard of care (SoC) for the treatment of adults with active systemic lupus erythematosus (SLE) who test positive for anti-double stranded DNA (Anti-dsDNA) and low complement (C3 or C4).

METHODS : A cost-effectiveness analysis (CEA) was conducted using a semi-Markov cohort model, described previously (Kelton et al. Value in Health, 2017). The analysis was run, from a private payer perspective and follows guidance from CADTH Guidelines for the Economic Evaluation of Health Technologies (4^th Edition). The model estimates costs and clinical benefits for each treatment valued by life-years (LYs) and quality-adjusted life-years (QALYs). Health states are defined by treatment status (belimumab or SoC), total SDI score, and SDI cardiovascular (CV) damage (present or absent). The disease characteristics of the patients in each health state are based on the selected population and are updated each cycle. Total costs, life-years, and QALYS were accumulated annually over a lifetime time horizon. The Incremental Cost-Effectiveness Ratio (ICER) and Incremental Cost Utility Ratio (ICUR) were calculated.

RESULTS : The lifetime incremental discounted costs, life years gained and QALYS gained for belimumab IV vs SoC were $70,792, 0.80, and 0.6957, respectively. The belimumab SC vs SoC analysis yielded an incremental cost of $70,770 and the same incremental life years and incremental QALYS gained as IV. The ICER for belimumab IV vs SoC was $88,493 while the ICUR was $101,757. The ICER for belimumab SC vs SOC was $88,465 and the ICUR was $101,726.

CONCLUSIONS : Belimumab IV and SC increased survival and quality of life for a mean lifetime cost of about $70,800. Belimumab demonstrates an ICER that is comparable to other biologics available in the immunoinflammation therapeutic area.