Disease Rates Worse in Nonwhite Kidney Donors

Disease Rates Worse in Nonwhite Kidney Donors
By John Gever, Senior Editor, MedPage Today
Published: August 18, 2010
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

Action Points

* Explain to interested patients that living black and Hispanic kidney donors had higher rates of hypertension, diabetes, and end-stage renal disease after seven years of follow-up than white donors.

* Note that the study authors concluded that follow-up should be more vigilant for all living donors, not that exclusion critieria should be more stringent for nonwhite donors.

Racial disparities in chronic disease prevalences seen in the general population are also apparent among living kidney donors following surgery, researchers said.

Rates of hypertension, type 2 diabetes, and chronic kidney disease were from 50% to 194% higher in black kidney donors relative to whites through a median of 7.7 years of follow-up after donation, according to Krista Lentine, MD, of St. Louis University, and colleagues.

The researchers found that Hispanic donors also faced higher rates of these diseases than did whites, according to their report in the Aug. 19 issue of the New England Journal of Medicine.

For the most part, rates of these conditions among donors were similar to those in the general population for each racial-ethnic group. The exception was that, among Hispanics, donors were more likely than nondonors to develop hypertension.

"Race and ethnic group should not be used to discourage donor evaluation, but these data may increase awareness of variation in long-term outcomes among living donors and of the need for longer in-depth follow-up of demographically diverse living donors," Lentine and colleagues wrote.

The researchers obtained insurance claims data on chronic diseases in 4,650 living kidney donors from 1987 to 2007. The median duration of eligibility in the insurance plan providing the data was 2.1 years; the median time from donation to the end of eligibility was 7.7 years.

These data were converted to prevalence estimates using Cox regression analysis and left and right censoring to account for actual periods of insurance.

For the general population, the researchers relied on prevalences found in the 2005-2006 National Health and Nutrition Examination Survey (NHANES).

About three-quarters of the donors were white, 13% were black, 8% Hispanic, and 2% other racial-ethnic groups. The mean age at donation was 37, though among blacks and Hispanics it was about 34. Comparison with demographic data on all living kidney donors in the Organ Procurement and Transplantation Network system indicated that the sample was fairly representative.

Lentine and colleagues calculated the following hazard ratios for chronic diseases in black and Hispanic kidney donors relative to non-Hispanic white kidney donors:

* Hypertension: Black, 1.52 (95% CI 1.23 to 1.88); Hispanic, 1.36 (95% CI 1.04 to 1.78)
* Type 2 diabetes needing treatment: Black, 2.31 (95% CI 1.33 to 3.98); Hispanic, 2.94 (95% CI 1.57 to 5.51)
* Chronic kidney disease: Black, 2.32 (95% CI 1.48 to 3.62); Hispanic, 1.90 (95% CI 1.05 to 3.43)

Rates of cardiovascular disease (coronary artery disease, angina, heart failure, or acute events) were similar in all racial-ethnic groups.

These patterns differed in some respects from the racial disparities seen in the NHANES data. Hispanics in the survey had lower rates of hypertension than whites, for example (HR 0.65, 95% CI 0.51 to 0.83), whereas blacks had significantly higher rates of cardiovascular disease (HR 1.44, 95% CI 1.11 to 1.88).

But the estimated hypertension and diabetes prevalences for white and black kidney donors, stratified by age and sex, were similar to what was found in NHANES for these groups.

Hispanic donors, though, had much higher prevalence of hypertension than Hispanic participants in NHANES:

* 40-year-old females: 18.4% for donors (95% CI 13.4% to 23.1%), 10.4% in NHANES (95% CI 8.5% to 12.7%)
* 40-year-old males: 20.6% for donors (95% CI 14.9% to 25.8%), 9.8% in NHANES (95% CI 7.9% to 12.0%)
* 55-year-old females: 40.2% for donors (95% CI 30.5% to 48.6%), 21.6% in NHANES (95% CI 18.1% to 25.6%)
* 55-year-old males: 44.2% for donors (95% CI 33.3% to 53.3%), 20.5% in NHANES (95% CI 16.9% to 24.5%)

Lentine and colleagues indicated that they didn't believe these figures reflect a true increased risk for Hispanic kidney donors. Rather, they suggested that the NHANES data and other studies may have underestimated the actual prevalence of hypertension in this group.

"We speculate that medical surveillance after kidney donation may mitigate barriers to the recognition of hypertension," they wrote, noting that the prevalence among kidney donors in the study was about the same in Hispanics and blacks.

Not surprisingly, the researchers identified age at donation as a significant predictor of chronic disease. Each year of age increased the risk of hypertension, diabetes, and chronic kidney disease by 4% to 6%, and cardiovascular disease by 9%.

Limitations to the analysis included the different methods of disease ascertainment in the donor sample versus NHANES; potential errors and omissions in the insurance claims data; and the sample's inherent exclusion of uninsured individuals.

Data on body mass index also were not available.

The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

The authors reported they had no competing relationships with commercial entities.

Primary source: New England Journal of Medicine
Source reference:
Lentine K, et al "Racial variation in medical outcomes among living kidney donors" New Engl J Med 2010; 363: 724-732.

http://www.medpagetoday.com/Nephrology/KidneyTransplantation/21752