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 — specifically, black patients — 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 — 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 — 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 — 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 – 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 – 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 – 5.4), and the effect of low socioeconomic position remained relatively unchanged (HR, 2.1; 95% CI, 1.0 – 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.
Reviewed by Dr. Ramaz Mitaishvili
http://www.rmgh.net
