Social Determinants of Health (SDOH) and Access to CART for Multiple Myeloma

Background:

Multiple Myeloma (MM) is the most common hematologic malignancy in the black population, constituting 20% of all MM patients (IMF Website). Chimeric antigen receptor T-cell (CART) therapy has emerged as a valuable treatment option for MM. Based on lymphoma studies, it is known that CART access is disproportionately lower for blacks, those with inadequate insurance, and those from lower socioeconomic strata (SES). The University of Kansas Health System (TUKHS) is a center offering CART, with a volume of over 100 CART/year. The referral base primarily spans the states of Kansas (KS) and Missouri (MO). We aimed to evaluate barriers to access for MM CART at our center based on social determinants of health (SDOH) parameters.

Methods:

This retrospective study was conducted at TUKHS in collaboration with the US Myeloma Innovations Research Collaborative (USMIRC). We identified patients with MM who were referred for CART between January 2021 and December 2023. The primary outcome was to analyze the racial background, SES, and insurance as SDOH variables with the likelihood of leukapheresis for CART. An interim analysis was performed. Institutional policies included a requirement for a 24/7 caregiver for the first 30 days post-infusion and that patients reside within a 30-minute radius of the hospital. Patients living outside this range must arrange for lodging. Median household income and distance from the center in minutes was determined using 2022 zip code data from the US Census Bureau. Using R Core Team (2024) software, a descriptive analysis was performed. Continuous variables were summarized and reported as the mean (min, max) and median with IQR. Dichotomized factors were summarized by total counts and frequency. Fisher’s exact was used to analyze contingency tables. Wilcoxon rank-sum test was used to compare two independent samples for continuous variables.

Results:

During the study period, there were a total of 271 referrals for MM CART therapy, involving 179 patients. The median age of patients at time of referral was 66 (34-85) years, with 51% being male. Patient demographics were: 80% white, 16% black, 2.2 % other races, and 1.8% asian. The median income for all patients referred was $70,644 (31,250 – 207,534). Of all the patients referred, 49.7% lived beyond 30 minutes of the center. There were 59 patients that had multiple referrals with a median number of referrals per patient of 1 (1-5).

Out of 179 patients referred, were able to proceed to leukapheresis or receive an investigational allogeneic CART. No major differences were identified between whites, blacks, and other races in terms of the percentage of leading to apheresis with 54%, 54%, and 50% of patients respectively. All 3 asian patients did not proceed to collection. No significant difference was seen in the percentage of patients undergoing CART apheresis based on whether they resided in a zip code with income higher or lower than the median income (49% vs 55%, p=0.5). One patient was unable to receive insurance authorization for treatment. Similarly, no difference based on insurance type (Medicaid vs Medicare vs Commercial) existed (55% vs 49% vs 52%, p=0.4). Nine patients (5%) were not able to proceed due to barriers such as the lack of a caregiver (n=8) and insurance (n=1) No difference in cell collection based on whether patients lived within 30 minutes (34%) or further away (35%) from the hospital was found.

Conclusion:

The most important finding of this study is that the representation of blacks referred was comparable to the population of blacks in KS and in the Midwest, suggesting less disparity in CART access at our center for minorities. Amongst those who were able to get leukapheresis, distance from the center, median household income, and insurance did not differ. These findings are surprisingly better than national database reports for lymphoma CART where Medicaid, lower SES, and distance from the center have consistently been associated with lower access. This may reflect center effect, geographic variation, or patterns in MM, which may differ from lymphoma. We propose a larger national database study to understand the association of SDOH with CART access, specifically in MM, to identify national trends.