Tuesday, June 01, 2010

Race-Matching No Help in Heart Transplant Survival

By Michael Smith,
North American Correspondent, MedPage Today

Published: May 31, 2010
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine.

African Americans do significantly worse after a heart transplant than Caucasians, but not because they were getting racially mismatched organs, researchers said.

In a retrospective review of 20,185 heart transplant patients over a 10-year period, blacks had a 46% increase in the risk of cumulative mortality, compared with whites, according to Ashish Shah, MD, and colleagues at the Johns Hopkins Medical Institutions in Baltimore, Md.

But matching hearts to recipients on the basis of race did nothing to alter the odds of survival in any ethnic or racial group, the researchers wrote online in the Annals of Thoracic Surgery.

"It does not matter whether a white, black, Hispanic, or Asian donor heart is transplanted into a patient of any other particular race," Shah said in a statement. "Other factors must be the reason for any differences in how well people do after transplantation -- in particular, why blacks have poorer outcomes."

Shah added that the finding should reassure patients that they don't need a race-matched heart.

The researchers analyzed data from the United Network for Organ Sharing to analyze a range of factors that might be involved in survival after a heart transplant. The patients were stratified by race and ethnicity, as well as by donor-recipient race-matching.

Most of the patients in the study -- 76% -- were white, followed by 14.6% African Americans, and 6.4% Hispanics, and a handful from other groups. Most of the donors were also white -- some 72% -- followed by 12.1% African American and 13.5% Hispanic.

Of the 20,185 patients, 61% got a race-matched heart, including 74.5% of the whites, 17.5% of the blacks, and 30.3% of the Hispanics.

Over the 10 years of the study, 28% of the patients died, the researchers noted. The 10-year survival for blacks was 45.8%, which was 11.4% lower than the 57.2% for whites and 10.8% lower than the 56.6% for Hispanics. The differences were significant at P<0.001.

In a multivariate analysis, adjusted for a range of risk factors, African-American heart recipients had a 46% increase in cumulative mortality compared with whites (HR 1.46, 95% CI 1.24 to 1.72, P<0.001).

The authors noted that the study was limited by its retrospective approach. In addition, they wrote "the UNOS data set likely does not include all important confounders, such as detailed economic data germane to the question at hand."

Overall, patients getting a race-matched heart appeared to have a 4.4% increase in survival compared with those who did not. But no racial group had a significant benefit when stratified by race-matching, the researchers said.

The apparent discrepancy, they said, arises from the skewed distribution of race-matching -- with African Americans getting a race-matched organ markedly less often than whites.

"It is clear that race-matching does not improve survival" after heart transplant, the researchers argued, and so investigators must look elsewhere for explanations of the excess risk seen for African Americans.

Three possible biological explanations emerge from the data, they theorized -- African Americans were more likely to have hypertension before the transplant, to get a donor heart that had tissue antigen mismatches, and to get a donor heart mismatched for sex, although immune system mismatches lost significance in the multivariate analysis.

But social explanations may also play a role, they wrote. Patients on Medicaid, rather than private insurance, had a 39% higher risk of higher risk of death. And having a college education lowered the risk of issues linked to organ rejection by 12%.

The study's first author, Jeremiah Allen, MD, said the next step is to figure out which factors are different in those African Americans who do well after transplant, compared with those who do not. Allen noted in a statement that the study found that about 45% of African Americans with donated hearts lived longer than 10 years.

"This research is key to correcting the survival disparity in African Americans in surviving heart transplantation and helps us learn how to take better care of some of our most high-risk transplant recipients," he said.

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