The studies showed that a large proportion of potential donors are rejected on the basis of elevated body mass index (BMI).
The lead investigator of one of the studies, Zoe A. Stewart, MD, PhD, of the University of Iowa Hospitals and Clinics in Iowa City, noted that the U.S. has a growing prevalence of obesity such that 35% of adults are now considered obese, and this could impact live kidney donation.
“My hypothesis was that elevated BMI is a major factor for kidney donor candidate denial, and that this is one of the major reasons why we have failed to really see an increase in living kidney donors overall,” Dr. Stewart told colleagues.
Data from the Organ Procurement and Transplantation Network, the number of living donor transplants declined from 6,241 in 2002 to 5,770 in 2011 and 5,624 in 2012.
Dr. Stewart analyzed data from 450 living kidney donor candidates. Of these, 398 were rejected for donation and 52 were approved. Candidates who were rejected had a mean BMI of 28.9 kg/m2, which was significantly higher than the mean 25.9 kg/m2 for the approved group, Dr. Stewart reported.
Of candidates approved for donation, only 11.5% were obese (BMI above 30) and 88.5% were non-obese (BMI below 30). Regardless of whether candidates were obese or not, whites were more likely to be approved for donation than non-whites (12.3% vs. 5%-6% of blacks and other race/ethnicities). Among the obese, non-whites were never approved for donation, she reported.
Dr. Stewart noted that a BMI above 35 is an absolute exclusion criterion for donation at her institution. In the study, 42.5% of prescreen denials were due to a BMI above 35.
Among candidates denied for medical indications, the most common reason was hypertension (10.2%), followed by BMI greater than 35 (9.6%), renal disease (6.2%), and cardiovascular disease (2.9%).
Study results also showed that non-Caucasian race and education level less than a four-year college degree correlated with donation denial.
In the other study, Deonna Moore, MSN, and colleagues at Vanderbilt University Medical Center in Nashville, Tenn., analyzed data from 967 potential donors. Of these, 212 (22%) were ineligible to donate, and 140 of them (66%) were excluded because they had a BMI of 35 or higher. The mean BMI of excluded candidates was 39.7 kg/m2. The study found no difference in exclusion by race. The researchers presented their findings in a poster, where they concluded: “Weight loss programs are an important potential target for intervention to increase live kidney donation.”