Racial Disparities in Intravenous Bisphosphonate Use Among Older Patients With Multiple Myeloma Enrolled in Medicare

Abstract

PURPOSE: Intravenous (IV) bisphosphonates reduce the risk of skeletal-related events in patients with multiple myeloma (MM). However, data describing racial differences in IV bisphosphonate utilization outside of clinical trial settings are limited. We evaluated population-level IV bisphosphonate initiation and discontinuation among patients of age ≥ 65 years with MM. METHODS: We conducted a retrospective cohort study of patients of age ≥ 65 years diagnosed with first primary MM between 2001 and 2011. Patients were identified using the SEER-Medicare linked database and followed through December 2013. Cumulative incidences of IV bisphosphonate initiation and time to discontinuation among users were compared between racial and ethnic groups. In Fine and Gray competing risk models, we estimated subdistribution hazard ratios (SHRs) and 95% CIs for initiation and discontinuation. RESULTS: We included 14,231 eligible patients with MM (median age, 76 years; 52% male). Over a median follow-up of 23.1 months, 54% of patients received at least one IV bisphosphonate dose. Our final analytical sample included 10,456 non-Hispanic (NH) Whites, 2,267 NH Blacks, 548 Asian and Pacific islanders, and 815 Hispanic and Latino patients. A higher proportion of White patients (56.1%) newly received IV bisphosphonates after MM diagnosis compared with NH Blacks (45.4%). Compared with White patients, NH Black patients were less likely to initiate IV bisphosphonates (SHR, 0.74; 95% CI, 0.70 to 0.79) and slightly more likely to discontinue treatment (SHR, 1.10; 95% CI, 1.01 to 1.19). CONCLUSION: Approximately half of the patients with MM of age ≥ 65 years did not receive IV bisphosphonates, with significant delay among racial minority groups. These findings highlight the need for improvement of IV bisphosphonate uptake in patients with MM of age ≥ 65 years.