Many patients with acute myeloid leukaemia (AML) can be cured by a transplant of blood-forming stem cells from a healthy donor, known as an allogeneic haematopoietic cell transplant (HCT). Studies have shown, however, that for a variety of reasons HCT may not be equally available to patients with AML from all backgrounds.

A prospective study examining the impact of social determinants of health on access to and survival after allogeneic HCT for patients with AML has shown that patients living in neighbourhoods where more residents had less than a high school education, had incomes below the federal poverty level, or received benefits from federal assistance programs were less likely to receive HCT and more likely to die without receiving it. Among patients who did receive HCT, social and economic barriers, particularly lower education and use of federal assistance programs, were linked with a modest increase in mortality.

“To the best of our knowledge, this is the first prospective, multi-center study to evaluate the impact of specific social determinants of health on access to HCT and survival outcomes,” said first author Natalie Wuliji, DO, an assistant professor at Fred Hutchinson Cancer Center in Seattle. “Our results could set the stage to help identify targeted interventions to improve access to HCT for patients with AML who face socioeconomic barriers.”

AML is a fast-growing cancer of the blood-forming cells in the bone marrow. Previous studies that looked back at the records of patients treated in the past have suggested that patients with AML who have lower incomes or fewer years of education, belong to minority racial or ethnic groups, or lack private health insurance face more barriers to obtaining HCT than other patients. Other research has shown that social determinants of health – defined as the conditions in which people live and work, such as low income, low education level, food insecurity, and housing instability – can significantly affect health outcomes.

“We found that social and economic barriers have a greater impact on the ability to receive a transplant or on the risk of death before transplant than on outcomes after the transplant,” Dr. Wuliji said. “These findings suggest that access to allo-HCT may help level the playing field for AML patients across socioeconomic backgrounds, though further studies are needed to confirm this.”

HCT is costly, available at a limited number of specialised centers, and involves a lengthy hospital stay, Dr. Wuliji said – all of which impose burdens on patients and families who have limited resources, difficulty taking time off work to travel for care, or limited health insurance coverage.

For this study, Dr. Wuliji and her colleagues followed 692 adult patients for a median of 4.5 years after their AML diagnosis. The patients were treated at one of 13 medical centers across the U.S. The researchers collected data on how many patients received HCT and how many died before and after receiving HCT. They classified patients by the zip code in which they lived and examined U.S. Census Bureau data for those zip codes on a range of social and economic factors. These included median household income, the percentage of adults aged 25 or older with less than a high school education, and the percentage of households receiving Supplemental Security Income (SSI, a federal program for people with disabilities and low-income older adults), or Supplemental Nutrition Assistance Program (SNAP) benefits (also known as food stamps).

The research team also documented patient-reported race as a proxy for exposure to discrimination. They then used statistical methods to evaluate the effects of these social and economic factors on the patients’ likelihood of receiving HCT, dying without receiving HCT, and dying after HCT.

The patients’ median age was 62; 43% were aged 65 or over and 43% were female. Most (77%) had newly diagnosed AML with features associated with a poor outlook. Across all zip codes, 7.3% had less than a high school education; 9.5% had incomes below the federal poverty level; 10.2% received SNAP benefits; and 4.2% received SSI. Most patients (86%) self-identified as white, 6% as Black, 3% as Asian, and 4% as another race. Overall, 46% of patients received HCT; among those aged 65 or over, 31% received HCT.

A total of 291 patients died without receiving HCT. The risk of dying without receiving HCT increased by 24% as the proportion of zip-code residents with less than a high school education increased by 10%, by 40% for each increase in the proportion of residents receiving SSI, by 18% for each 10% increase in the proportion with incomes below poverty, and by 14% for each increase in the proportion receiving SNAP benefits.

The likelihood of a patient receiving HCT decreased by 30% as the percentage of zip-code residents with less than a high school education increased by 10%; by 22% for each 10% increase in households receiving SSI; by 5% for each 10% increase in households with incomes below poverty; and by 9% for each 10% increase in households receiving SNAP benefits.

Compared with white patients, Asian patients had a 34% higher likelihood of receiving HCT, Black patients an 18% reduced likelihood, and those of other races an 11% reduced likelihood. However, given the small percentage of non-white patients in the study, it is difficult to draw definitive conclusions about the impact of race on study outcomes, Dr. Wuliji said. The likelihood of receiving HCT increased by 5% with a $25,000 increase in median income in the zip code.

Among patients who received HCT, the risk of dying after the procedure increased by 17% as the percentage of zip-code residents with less than a high school education increased by 10%, by 22% as the percentage of households receiving SSI increased by 10%, and by 12% as the percentage receiving SNAP benefits increased by 10%. No increase in the risk of dying after HCT was seen for patients with incomes below poverty.

An ongoing trial aims to increase the participation of patients from groups underrepresented in clinical trials and to develop HCT-focused patient education materials, Dr. Wuliji said. Future plans include exploring novel ways to improve access to HCT for patients who live in neighbourhoods with lower education levels or poverty.

The impact of social and economic barriers on mortality among patients receiving HCT needs to be confirmed in future studies, Dr. Wuliji said. Limitations of the study are that its findings on SDOH are based on zip-code level data rather than patient-level data and that patients who could not understand or read English were excluded because patients were required to complete questionnaires and surveys that were available only in English, she said.

This study was funded by grants from the Patient-Centered Outcomes Research Institute, the American Cancer Society, and the American Society of Hematology.

The study was simultaneously published in Blood.

Source: ASH