Children from families with low socioeconomic status who undergo
heart transplantation have twice the risk for graft failure as
pediatric heart recipients from wealthier families, reported
investigators here at the International Society for Heart and Lung
Transplantation 28th Annual Meeting and Scientific Sessions.

Low socioeconomic position remained an independent risk factor for
graft failure in children even after controlling for multiple
clinical and demographic factors, said Tajinder P. Singh, MD, MBBS,
from the Department of Pediatric Cardiology at Children's Hospital
Boston, and an assistant professor of pediatrics at Harvard Medical
School.

"This is really the first time, in children, that this has been
looked at from a socioeconomic as opposed to a racial standpoint,"
said session moderator Robert J. Boucek, MD, chief of the Division
of Cardiology at Seattle Children's Hospital and Regional Medical
Center, in an interview with Medscape Transplantation.

"Several studies previously demonstrated that there is an
association between race, so that nonwhites ¡X specifically, black
patients ¡X have worse long-term survival," Dr. Singh said in an
interview. "[T]hey seem to have more rejections of the heart
transplant, and there is a lot of emphasis on genetic and
immunologic studies to differentiate different races and how their
biology is different."

Dr. Singh continued, "Based on some clinical observations, I
wondered whether somebody had systematically looked at the
socioeconomic data in these people. The problem is we in medical
records do not record what the patient or family income is, what the
parents education is, what occupation they're in ¡X maybe
occupation, but it's not systematically and consistently written
down."

Zip codes, which some investigators use to identify patient
demographic, social, and financial characteristics, cast too wide a
net and may skew averages too heavily in one direction or another,
Dr. Singh said. To get around this problem, he and his colleagues
used block groups ¡X the smallest units available in US census
databases that also contain socioeconomic data.

"All data on block groups are reported every 10 years by the US
census bureau; it's meant to be permanent, and it's meant to be
relatively homogeneous with regards to people's socioeconomic
status ¡X it's literally your neighborhood," he said.

The investigators looked at US census data from 2000, extracting
data on 6 variables of wealth, income, education, and occupation for
each transplant recipient. They then calculated a summed
socioeconomic z-score for 126 heart transplant recipients who
survived to discharge at Children's Hospital Boston from 1990 to
2005.

They also created multivariate Cox proportional hazards models to
determine the risk of graft failure, defined as time to death or to
retransplantation, for the children in the lowest tertile of
socioeconomic status compared with those in the middle and upper
tertiles, who served as control patients.

The patients ranged in age from 6 days to 23 years (median, 8.9
years) at the time of transplant. The distribution of age, sex,
diagnosis, and treatment year was similar among the groups. Whites
accounted for significantly fewer children on the lowest rung of the
socioeconomic ladder, at 67% vs 90% of control patients (P < .01).

In all, there were 37 graft failures. The authors found in a
univariate analysis that being in the low-socioeconomic group was
associated with a more than 2-fold risk for failure (hazard ratio
[HR], 2.3; 95% confidence interval [CI],1.2 ¡V 4.4), and being a
member of a nonwhite race was associated with a nearly 3-fold
increase in risk (HR, 2.9; 95% CI,1.4 ¡V 5.9).

In multivariate models controlling for patient age, diagnosis (eg,
congenital heart disease vs dilated cardiomyopathy), transplantation
era, and race, the effect of race on graft failure was slightly
attenuated but still significant (HR, 2.5; 95% CI,1.2 ¡V 5.4), and
the effect of low socioeconomic position remained relatively
unchanged (HR, 2.1; 95% CI, 1.0 ¡V 4.3; P = .04).

All of the children in the study, both rich and poor, were insured,
Dr. Boucek noted, suggesting that "it's not an issue of access, but
it may be care before leading to transplant that accounts for the
differences."

The Children's Hospital Boston researchers will be expanding the
study to look at a larger population, with centers in New York City,
Atlanta, and Loma Linda, California, and to look at data on both
children and adults transplanted in Boston hospitals over the last
decade.

Dr. Singh and Dr. Boucek have disclosed no relevant financial
relationships.

International Society for Heart and Lung Transplantation 28th Annual
Meeting and Scientific Sessions: Abstract 192. Presented April 10,
2008.

J Heart Lung Transplant. 2008;27(2 suppl):S129.