Net costs associated with inpatient (IP) administration of step-up dosing (SUD) of bispecific antibodies (bsAbs) among Medicare patients (pts) with relapsed/refractory multiple myeloma (MM).

Abstract

e19504 Background: Initiation of bsAbs requires SUD with close monitoring, typically in IP settings, to mitigate early toxicities. As bsAb use expands, it is crucial to understand the financial viability for administering bsAbs, particularly non–PPS-exempt hospitals paid via a capitated, DRG-based method where costs may exceed payout. We compared net costs and payments for Medicare pts initiating bsAbs in the IP setting at non-PPS-exempt hospitals and explored cost variations for hospital characteristics and adverse events (AEs). Methods: Using Medicare FFS Parts A/B claims (10/25/21–10/20/24), pts ≥65 years with MM, IP bsAb initiation, and 12 mos continuous pre-index coverage were identified. Pts receiving other MM therapies <30 days post-index or treated in PPS-exempt hospitals were excluded. Hospital costs were estimated by applying revenue center–specific Medicare cost–charge ratios from CMS Hospital Cost Reports to IP facility charges. Outpatient (OP) bsAb costs were estimated using ASP/unit administered/wasted at the time of the claim. Costs for other OP services were estimated using revenue center–specific cost–charge ratios. Medicare payments were defined as total allowed amounts on IP and OP claims, and net cost as payments minus estimated costs. IP resource use and net cost recovery by academic vs nonacademic hospital, length of stay (LOS), and AEs were analyzed. Results: Of 3074 pts with a bsAb claim, 1129 met inclusion criteria. Mean IP LOS was 9 days (range 1–68). Hospital mean estimated IP cost/day for index hospitalization was $3963. Mean estimated costs for index hospitalization were $36964 per pt for IP SUD and $28366 for mean Medicare payments with a mean loss of $8598 per pt (median −$5616). Payments exceeded estimated costs on average by $2764–8149 for 1–4-day hospitalizations and roughly equal costs for hospitalizations at 5 days. For pts with LOS of 6–9 days and ≥10 days, payments were lower than costs by $6735 and $16659, respectively, suggesting a loss. For pts with subsequent OP administrations (74%) observable in this sample, cumulative payments and costs were assessed following the index hospitalization, mean cumulative longitudinal payments were ≥ cumulative costs within 2–3 mos. IP stay net losses were higher among pts with infection (−$6406 vs no infection), neutropenia (−$7006), and febrile neutropenia (−$10018). Payment patterns and estimated costs were similar across hospital types. Conclusions: Results suggest a large financial burden on non-PPS-exempt hospitals for IP-administered bsAb SUD. While shorter LOS for IP SUD generally did not result in financial losses, longer LOS was associated with disproportionately higher costs relative to payments. Care models (e.g. OP SUD) are key to manage initiation costs and ensure delivery of care for bsAbs remains financially sustainable.