Evaluating factors influencing receipt of stem cell transplant and time to transplant at a diverse metropolitan transplant center: Do racial disparities persist?

ASH: 60th American Society of Hematology Annual Meeting & ExpositionH Shah, S Kim, S Klimecki, JP Uberti, CA Schiffer, EK Seymour | December 02, 2018

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Summary: In this large, retrospective study, researchers assessed the presence of disparities in the use of stem cell transplant (SCT) based on age, race, and insurance type in a large metropolitan SCT center with a large population of minority patients. They concluded that race, age, and diagnosis are independent significant factors impacting receipt of SCT. Race and insurance status were independent factors associated with more prolonged time to SCT. In addition, they found that the effect of racial disparities in receipt of SCT and time to SCT are declining over time.

Methods:

  • Researchers included 2,811 patients at Karmanos Cancer Institute who had their initial SCT consultation between 2009 and 2016, and evaluated those who received or did not receive SCT for the diagnoses of acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), myelodysplastic syndrome (MDS), multiple myeloma (MM), or non-Hodgkin lymphoma (NHL).
  • Using logistic regression modelling, they studied the associations of SCT receipt status with four chosen predictors: age at the initial SCT consult (continuous variable), race (Caucasian vs Non-Caucasian), sex, diagnosis (AML/ALL vs MDS vs NHL vs MM).
  • In patients who did receive SCT, they calculated time to SCT from the date of coordinator intake (date of 1st SCT consult + screening initiated) to the date of SCT.
  • Researchers then used Kaplan-Meier estimates to summarize the distributions of time to SCT, and Cox proportional hazards regression models to assess associations between seven prespecified predictors, including age, race, sex, diagnosis, type of SCT (auto vs allo], county (metro [three counties within Metro Detroit] vs non-metro), and insurance (private vs public [Medicaid, Medicare, others]) and time to SCT.

Results:

  • In all, 1,644 patients received SCT.
  • Upon their multivariable analyses, researchers found the following groups less likely to receive SCT:
    • non-Caucasian (n=585 with 495 African-Americans) compared with Caucasian (n=2226) (OR: 0.68, P < 0.001, 95% CI: 0.56-0.83);
    • NHL pts (n=750) compared with MM (n=1136) (OR: 0.38, P < 0.01, 95% CI:0.31-0.46) or AML/ALL (n=642) (OR: 0.76, P=0.01, 95% CI: 0.61-0.95); and
    • older patients compared with younger (OR: 0.97, P < 0.001, 95% CI: 0.97-0.98).
  • They observed an interaction of race with both age and diagnosis; and performed propensity match scoring analysis to reduce selection bias due to these interactions (matching Caucasians and non-Caucasians by age and diagnosis), resulting in 1,170 matched pts.
  • When conducting multivariable analysis among matched patients, they found that that older compared to younger, non-Caucasian compared to Caucasian, and NHL pts compared to MM pts were less likely to receive SCT and remained independently significant.
  • Interestingly, differences in ORs of SCT between non-Caucasians and Caucasians depended on the year of initial consultation, and diminished over time.
  • Researchers also evaluated all patients who received SCT (n=1,631), of whom 1,307 (80%) were Caucasian and 324 (20%) were non-Caucasian (273 were African-Americans).
  • Median time to SCT was 3.24 months for all and 75% underwent transplantation by ~4.5 months.
  • Upon multivariable analysis, they found significanlty longer times to SCT in the following:
    • non-Caucasian (median: 3.8 months) compared with Caucasian (median: 3.28 months) (HR: 0.75, P < 0.01, 95% CI 0.65-0.85);
    • public insurance (n=800, median: 3.43 months) compared with private insurance (n=831, median: 3.28 months) (HR: 0.90, P=0.04, 95% CI: 0.81-0.99);
    • auto SCT (n=983, median: 3.51 months) compared with allo SCT (n=648, median: 3.1 months) (HR: 0.82, P < 0.05, 95% CI: 0.67-0.99); and
    • NHL pts (n=360, median: 3.57 months) compared with AML/ALL patients (n=367, median: 2.95 months) (HR: 0.74, P < 0.01, 95% CI: 0.61-0.90).
  • Researchers also performed propensity matched scoring analysis between races to reduce selection bias due to the association of race with age, county, type of SCT, insurance, and diagnosis, resulting in 624 matched pts.
  • After matching, multivariable analysis still showed non-Caucasian and public insurance to be independent factors in delay to SCT; but differences in HRs of time to SCT between races depended on the year of consultation and improved over time. 

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