The effect of out-of-pocket costs on initiation of disease-modifying therapies among medicare beneficiaries with multiple sclerosis

Abstract

BackgroundMedicare beneficiaries with multiple sclerosis (MS) often face high out-of-pocket (OOP) costs for disease-modifying therapies (DMTs). It is unclear how cost-sharing affects therapy initiation. ObjectivesTo estimate the effects of patient cost-sharing on initiation of a DMT among Medicare beneficiaries with a new diagnosis code for MS. MethodsUsing Medicare claims data from 2010 to 2014, we identified a cohort of individuals with at least one inpatient or two outpatient diagnostic claims for MS. We restricted this group to beneficiaries with continuous Part A, B, and D coverage in the year before and after their initial diagnosis. To estimate the effect of cost-sharing on time to self-administered DMT initiation, we compared beneficiaries with a Low-Income Subsidy (LIS), who are shielded from cost-sharing, to those without LIS using multivariate Cox Proportional Hazards models adjusting for potential demographic and health-related confounders. ResultsThere were 39,661 Medicare beneficiaries who met inclusion criteria; 3827 had full LIS benefits throughout the study period. Beneficiaries were predominately White (36,447, 91.9%) and female (29,406, 74.1%). LIS recipients were generally younger (55 vs 67 years, p<0.001) and more likely to be enrolled through disability eligibility (79% vs 36%, p<0.001). In the year after their index diagnosis, 434 LIS recipients initiated DMT versus 1682 non-LIS (11% vs 5%; p<0.001). Among those who started a DMT, the average time to initiation was 115 days in those with LIS and 137 days for non-LIS (p<0.001). After adjustment for covariates, individuals with LIS benefits were significantly more likely to initiate a DMT in the year following their diagnosis (adjusted hazard ratio 1.4, 95% CI 1.25 to 1.57). The effect of OOP costs on initiation did not differ by demographic subgroups. ConclusionsMedicare beneficiaries with MS who are shielded from traditional cost-sharing are more likely to initiate a DMT in the year following receipt of their first diagnosis code. Future work should examine the effect of cost-related treatment delays on relapse rates and disability progression.