By Nelson Chao, MD
2008-03-01
Dr. Chao indicated no relevant conflicts of interest.
Rao K, Darrington DL, Schumacher JJ, et al. Disparity
in survival outcome after hematopoietic stem cell transplantation for
hematologic malignancies according to area of primary residence. Biol Blood Marrow Transplant. 2007;13:1508-14.
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As a community, we have learned much about risk factors for patients
undergoing hematopoietic cell transplantation (HCT). Some factors
reflect the patient and his or her physique. The most primitive scale
has been the Karnofsky or the ECOG performance statuses, both of which
are still widely used but are fairly crude measurements. The more
recent adoption of comorbidity scales has significantly improved our
ability to predict which patients are at very high risk for HCT. Other
factors reflect the malignancy, such as the stage of the disease, the
remission status, the cytogenetics of the tumor, disease sites, and
number of prior therapies, to name a few. These measurements reflect
the individual and the biology of the malignancy in that particular
person ― more of the nature of the disease. But what about nurture?
Specifically, are there factors in the patient’s environment that could
make a difference?
Some of the earliest applications of ZIP code data were for use in
customer acquisition promotions, direct mail, and telemarketing. If one
lived in a high-rent district, it would be a prime area for marketing.
In contrast, poor or rural areas were spared. The rationale was obvious
in that the high-rent districts had access to disposable income and
perhaps better services. This process of targeting specific ZIP codes
has continued precisely because it worked well. If this is the case,
then the reverse should also be true. Poorer or rural areas could be
expected to have less disposable income and poorer services, including
access to health care.
A recent paper published in Biology of Blood and Marrow Transplantation
explored whether a patient’s area of primary residence is an
independent risk factor for overall survival (OS) after HLA-identical
sibling or autologous HCT. This was a retrospective cohort study that
included patients who had undergone autologous (n=1739) or
HLA-identical sibling (n=267) HCT to treat a hematologic malignancy
between 1983 and 2004 at the University of Nebraska Medical Center.
Primary area of residence, using the patient’s ZIP code, was
categorized as either urban or rural (including isolated, small rural,
or large rural), according to the Rural Urban Commuting Area Codes
(RUCA) classification system. An association between area of primary
residence and survival was examined using Cox proportional hazards
regression analysis while adjusting for patient-, disease-, and
treatment-related variables. Patients from rural areas who received
autologous HCT had a higher relative risk (1.18) of death compared to
urban patients. Survival rates in patients from rural and urban
locations were as follows: one year, 73 percent versus 78 percent
(P=.04); five year, 48 percent versus 54 percent (P=.012). There were
no differences in the allogeneic population, although the number of
patients was more limited.
It is important to recognize that this was a
retrospective analysis, and thus there were no controls for important
variables such as comorbidities, income, distance traveled, educational
status, etc. However, these data raise interesting questions since the
disparity in survival was related to treatment toxicity. Many of these
toxicities, especially those in the intermediate to long term, are
preventable or treatable if detected early. Moreover, some of the
toxicities, such as interstitial pneumonitis in autologous HCT, are
frequently recognized and treated in transplant centers. However, in a
more rural community under the care of a general practitioner, this
complication may not be readily recognized and treated. The distance
that a patient has to travel may also affect how often or even whether
a patient wants to return for a follow-up visit to a transplant center.
These data do raise important issues for planning for discharge, and a
comprehensive plan for communications and follow-up should be in place
for all patients. While health-care inequities are not new, they should
not be ignored.
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