Racial Disparities in Treatment Utilization for Multiple Myeloma

Background:Recent treatment advances have greatly improved the prognosis of patients with multiple myeloma (MM). However, the utilization of some of these newer treatments is still low, particularly among black patients. Researchers initially attributed this disparity to access barriers such as lower socioeconomic status (SES) and/or inadequate health insurance. However, my colleagues and our group recently reported that black patients treated at our institution were 54% less likely to undergo stem cell transplantation (SCT) after controlling for these potential access barriers (Fiala, et al, BBMT, 2015).

In this study, we aimed to confirm our previous finding on racial disparities in SCT utilization using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. We also reviewed the utilization patterns of bortezomib (BTZ), a topic not reported on to date. We chose BTZ as a comparator as it has largely become the standard of care in recent years and, unlike SCT, BTZ is not exclusive to specialized centers.

Methods: All MM cases in the SEER-Medicare dataset from 2000-2011 were reviewed along with their corresponding claims data through 2013. We excluded cases with incomplete records such as: death certificate or autopsy cases, cases not enrolled in Medicare Part A and Part B, or did not have >1 claim one year prior to diagnosis, and managed care (HMO) enrollees; and cases where reported race was not white or black or where MM was diagnosed prior to age 65.

The presence or absence of the corresponding procedure codes for SCT and BTZ were used to determine their utilization. Multivariate logistic regression was performed to analyze the impact of race on treatment utilization controlling for baseline health measures (age at diagnosis, performance status [PS] indicators, and Charlson Comorbidity Index [CCI] Score) and potential access barriers (SES [measured by the median household income (MHI) of census tract of home residence], Medicaid enrollment, and urban/rural status).

The analysis of SCT utilization was limited to patients < 78 years old at diagnosis as coverage for SCT in older patients was previously restricted; BTZ utilization to patients diagnosed after 2003 to coincide with its FDA approval. We then performed multivariate Cox regression to analyze how the utilization patterns of these two treatments impact overall survival.

Results:A total of 11,269 patients were included in the analysis of SCT utilization and 16,037 for BTZ utilization. The 8,625 patients included in both were included in the survival analysis.

Overall, 84% were white and 16% were black. Black patients were younger at diagnosis (75.9 years compared to 77.3 years, p < 0.0001), but were more likely to have indicators of poor PS (27% compared to 19%; p < 0.0001), and a CCI > 1 (59% compared to 47%; p < 0.0001). Black patients also had lower SES on average (MHI $35,500 compared to $52,400; p < 0.0001) and were more likely to be Medicaid beneficiaries (34% compared to 11%, p < 0.0001).

After controlling for overall health and potential access barriers, black patients were 37% (aOR = 0.63 [95% CI 0.49-0.80], p < 0.0001) less likely to utilize SCT, and 21% (aOR 0.79 [95% CI 0.72-0.88], p< 0.0001) less likely to utilize BTZ. The underutilization of these agents was the associated with a 12% (aHR 1.12 [95% CI 1.05-1.19], p = 0.0007) increase in hazard ratio for death among black patients.

Conclusion: Eliminating health disparities is a current focus of U.S. public policy. This study highlights the complexity of the issue. In patients with MM, treatment disparities are not completely explained by poorer baseline health or increased access barriers among black patients. Differences in individual decision-making among black and white patients may explain part of the disparity.