Association of Patient Cost Sharing and Area Deprivation with Multiple Myeloma Treatment Receipt and Outcomes

Abstract

Introduction: Advances in multiple myeloma (MM) treatment have improved survival, but there are increased concerns about treatment affordability and access. This study assessed 1) how cost-sharing assistance and area deprivation affect treatment receipt, 2) changes in the patient cost responsibility and disparities in treatment over time, and 3) how the low-income subsidy (LIS), which lowers Part D cost sharing, and area deprivation affect treatment access and survival.

Methods: Using the Surveillance, Epidemiology, and End Results-Medicare database, we identified patients diagnosed with MM. The effect of cost-sharing assistance and area deprivation on treatment was estimated using multilevel logistic regression. We estimated the monthly incremental patient cost responsibility among MM patients compared to non-cancer controls and examined changes over time (2007-2011, 2012-2016). The effect of diagnosis period and area deprivation on treatment was estimated using multilevel logistic regression. The association between LIS, area deprivation, and mortality was estimated from a mixed-effects Cox proportional hazards model. We assessed whether treatment mediates the association between LIS and mortality.

Results: Individuals receiving Medicare Parts A, B and D cost-sharing assistance had higher odds of receiving treatment compared with non-recipients (OR=1.21; 95%CI: 1.01–1.45). Living in the most deprived area (Quintile 5) was associated with lower odds of receiving treatment compared with the least deprived area (Quintile 1; OR=0.81; 95%CI: 0.65–0.99), but there was no difference in the other quintiles. The difference in the estimated monthly incremental patient cost responsibility between 2012-2015 and 2007-2011 was $58 [average marginal cost; 95%CI: $12–$105]). The difference in the likelihood of any treatment receipt between Quintile 1 and 5 decreased, but the difference in the likelihood of receiving a novel agent-based regimen increased. The mortality hazard was higher for LIS recipients relative to non-recipients in Quintiles 1, 3 and 4 (HR=1.50, 1.38, 1.28; p=0.0001), and there was no difference in the other two quintiles. This association was partially mediated by treatment receipt.

Conclusions: The patient cost responsibility for MM care increased over time. The type of cost-sharing assistance and area deprivation affect treatment receipt, although not across all quintiles. LIS receipt did not confer a survival benefit.