Patterns of Utilization and Outcome of Hematopoietic Stem Cell Transplantation Among Various Cancers: A Nationwide Analysis

Introduction: Hematopoietic stem cell transplantation (HSCT) or bone marrow transplantation (BMT) is performed to treat hematologic malignancies such as acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), multiple myeloma (MM), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), myelodysplastic syndrome (MDS), lymphomas (HL and NHL) and hemophagocytic lymphohistiocytosis (HLH). Inpatient data on the characteristics of patients receiving BMT, the distribution of BMT among the above mentioned hematological cancers and their outcomes is lacking. This study analyzes patient and hospital characteristics of patients undergoing BMT, in addition the study describes resource utilization and outcomes of BMT among various hematological cancers.

Methods: We performed a retrospective cohort analysis of the National Inpatient Sample 2014 Database (HCUP-NIS). Patients were included in the study if they had a procedure diagnosis of BMT and a medical diagnosis of acute or chronic leukemia (ALL, AML, CLL, CML), lymphoma (HL and NHL), MM, MDS or HLH. HSCT or BMT includes both Allogeneic and Autologous Stem Cell Transplant however we did not differentiate one from the other since BMT in MM is almost universally auto stem cell transplantation. We performed descriptive statistics to characterize the cohort in terms of personal demographic factors (age, race, sex, insurance type, community level income level), indication for HSCT, hospital characteristics (size, region, teaching status, and urban or rural location), and timing of admission (weekend or weekday). We performed univariate analyses using these variables to determine the associations with LOS and mortality. All analyses apply the HCUP-NIS weights.

Results: The cohort comprised of 18,275 patients who underwent HSCT. Most patients were male (59.1%), white (70.4%), aged 51-70 years (53.9%), and covered by private insurance (57.0%). Nearly a third (31.3%) lived in communities with the highest quartile of household incomes. The most common diagnosis associated with HSCT was MM (27.6%), followed by AML (15.6%). Most HSCT was performed at large hospitals (74.5%); only 0.1% were performed in rural and 1.1% at non-teaching hospitals. Average length of stay (ALOS) was 25.54 days (95% CI 24.19 to 26.89) and the mean total charges (per hospitalization) were $346,555 (95% CI $310,465 to $382,645) and net charge was $6.33 billion. Several factors were associated with lower ALOS: age (AMD -0.31, 95% CI -0.37 to -0.24), Charlson index (AMD -0.85, 95% CI -1.60 to -0.12), private insurance coverage (AMD -3.65, 95% CI -5.25 to -2.067) and self pay status (AMD -13.56, 95%CI -17.13 to -10.00). Urban (AMD 6.74, 95% CI 1.01 to 12.48), and teaching hospitals (AMD 8.31 95% CI 2.88 to 13.72) had longer ALOS. Only Hispanic race (OR 0.23 95% CI 0.068 to 0.77) and Charlson index (OR 1.2 95% CI 1.04 to 1.39) were associated with mortality. Multivariate analysis did not show any significant associations of mortality with age, race, geographic region, hospital size, median household income, type of insurance, timing of admission, or teaching or location status of hospitals.

Discussion: MM accounted for the most significant portion of HSCT in 2014, although its incidence is lower than that for leukemia and lymphoma. This may partly be because autologous stem cell transplantation (ASCT) after high dose chemotherapy is the mainstay of MM treatment. In contrast to other hematological malignancies, some MM patients may also undergo tandem transplantation. Most HSCT recipients were covered under private insurance, and a significant proportion of them came from communities with the highest quartile of median household incomes. This suggests that socioeconomic status influences access to HSCT therapy, likely related to out of pocket costs. In addition, social determinants of health including health literacy, access to health care may play a role. Surprisingly, ALOS decreased with increasing age and Charlson comorbidity index. Reasons are unclear but may be related to increased or earlier mortality. Additional studies could help to elucidate this relationship.

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