If someone receives bone marrow from a donor of a community of lower socioeconomic status, that recipient may be more likely to die.
This is according to new research from the University of Minnesota Medical School and the Center for International Blood and Marrow Transplant Research, a research collaboration between the Medical College of Wisconsin and NMDP (formerly Be The Match and the National Marrow Donor Program).
Those conducting the study examined the health outcomes of 2,005 cancer patients who, from 2000 to 2013, received allogeneic hematopoietic cell transplants, or transplants of bone marrow from unrelated donors. The results were evocative: those who received transplants from donors who were in the lowest quartile of socioeconomic status were 6.6% more likely to die three years after the transplant. These recipients also had 9.7% lower overall survival compared to those receiving transplants from the highest socioeconomic quartile.
As a result, “cancer patients who received cells from individuals in the highest socioeconomic status had about a 10% survival advantage over those who received stem cells from the lowest socioeconomic status group,” explained Dr. Lucie Turcotte, one of the primary investigators of the study and associate professor at the University of Minnesota Medical School.
To measure and determine the socioeconomic status of the donors, researchers analyzed the ZIP codes where the donors lived. Each ZIP code received a composite score based on five factors – median household income, the percentage of families living below the poverty line, the percentage of unemployment, education level and renter occupied housing units. All of these factors, said Turcotte, were equally weighed to determine a ZIP code’s final score.
The reason for using ZIP codes to determine donor socioeconomic status was a result of data available from the Center for International Blood and Marrow Transplantation Research.
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“They collect data on essentially every patient and donor that go through unrelated transplants from another individual,” said Turcotte. “What they collect is readily available data on things like address (and) ZIP code. They don’t necessarily have that granularity of data on each individual on some of those socioeconomic variables of interest to us.”
“What we learned in some of the things we looked at is ZIP code is more related to outcomes than just individual address,” said Dr. Jennifer Knight, the other primary investigator involved in the study and professor at the Medical College of Wisconsin. “(It) turns out actually – and other research supports this too – that more of your overall living environment community is more important than your one individual income or address.”
The effects of living in a lower socioeconomic status community, the study found, are also independent of other factors. Turcotte noted that “even when adjusting for the center that they were treated, their insurance status, their race, ethnicity … and all of the disease characteristics of the cancer patient,” the difference in outcomes based on the socioeconomic status of the donor’s community still held true.
Knowing that donors from communities of lower socioeconomic status may lead to worse outcomes has a distinct impact on transplants. However, it’s the wider implications of this study – the impact of a person’s lived environment on their cellular biology – that may be especially impactful.
“If we can potentially (have) a 10% improved outcome for (donor recipients) based on one more variable for matching, that’s great,” said Turcotte. “But what that doesn’t really address is the bigger issue and the public health implications. If the biologic effects of poverty or of social disadvantage are so strong that you can actually take the cells out of one person and plant them into someone else and they persist overtime to cause (the recipient) worse health outcomes, what is happening to the person who you’re taking the cells from, (who is) living with those cells all of the time?”
It was because of the larger implications of this research that the findings were not published in an oncology journal, but a general science journal – something Turcotte believes will lead to a “broader readership,” including those working in public health or policy. It was published July 15 in the Proceedings of the National Academy of Sciences.
Others working in health care have noted the importance of this study for future research and for addressing the social factors impacting human health.
“This incredible work by Dr. Turcotte and colleagues should provide the foundation for further investigations of the impacts on previously undiscovered implications of socioeconomic challenges in healthcare,” wrote Dr. Nathan Gossai, pediatric oncologist at Children’s Minnesota in an email to MinnPost. “As social determinants of health impact all patients, all members of the medical community should be aware of these findings. The innovation and importance of this work should not be underestimated, (as) it may be the basis for significant advancements in our understanding of the impact of social determinants of health.”
Ann Nyakundi, the executive director of Minnesota Community Health Workers Alliance, who previously worked at NMDP, noted since a person must meet certain health requirements to be a donor at all, the findings are all the more troubling, as “at that cellular level, we carry with us disparities in society that we can’t escape.”
“When I worked at the National Marrow Donor Program, we called (the dates people received transplants) anniversaries,” added Nyakundi. “Those are like their birthdays because of how big of a procedure it is and how difficult it is. From a clinical perspective, for the person, it literally is like being born again (with) the replacement of those cells. When they get the treatment, they’re inheriting the disparities that existed (in) the person who, in a way, gave birth to their new life.”
Editor’s note: This story has been updated to clarify that the Medical College of Wisconsin worked on the research with NMDP (formerly Be The Match and the National Marrow Donor Program) through the Center for International Blood and Marrow Transplant Research.
Deanna Pistono
Deanna Pistono is MinnPost’s Race & Health Equity fellow. Follow her on Twitter @deannapistono or email her at dpistono@minnpost.com.
