Despite public awareness campaigns and innovative approaches such as kidney paired donation, living kidney donation (LKD) in the U.S. has been declining.

Data from the Organ Procurement and Transplantation Network (OPTN) show that the number of living donor transplants increased from 1,817 in 1988 to a peak of 6,647 in 2004, and then dipped to 6,573 in 2005. In 2013, 5,735 LKDs took place. The decline in living donor transplants has occurred mainly among blood relatives, OPTN data show.

The number of recipients receiving a kidney from a living blood relative (such as a parent, child, or sibling) decreased from 4,340 in 2004 to 2,886 in 2013 (a 33.5% drop), whereas the number of recipients of a kidney from a living donor who is not a blood relative (such as a spouse or an anonymous donor or an unrelated individual participating in a paired donation) actually increased during that period from 2,307 to 2,847 (a 23.4% increase).

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Nephrologist Jane C. Tan, MD, an associate professor of medicine at Stanford University in Palo Alto, Calif., pointed out that living donation may have spiked in the early to mid 2000’s due to multiple reasons, including increased public awareness, greater use of donor chains, and desensitization protocols, and this “gave a transient bump in living donation.”

“This would be the ‘low hanging fruit’ phenomenon,” said Dr. Tan, who is a member of the American Society of Nephrology’s Transplant Advisory Group (TAG). “Those who were eligible and very ready to donate did so during that era. To what extent the recent downward trend represents additional barriers to living donation or a new steady state is yet unclear.”

Medical exclusions

Michelle A. Josephson, MD, professor of nephrology at the University of Chicago and chair of TAG, said the LKD decline may be due in part to a growing prevalence of obesity, diabetes, and hypertension in the U.S. As a result, increasing numbers of potential donors may have these medical conditions, which are common reasons for medically ruling out individuals as donors, Dr. Josephson said.

Research findings document that medical conditions are a major reason for donor exclusion. In a study of 484 prospective living kidney donors at Stanford’s transplant center, Dr. Tan and colleagues found that 229 individuals were excluded from donation. Of these, 150 were excluded for medical reasons, mainly obesity, hypertension, abnormal glucose tolerance, and nephrolithiasis, according to results published in Clinical Transplantation (2011;25:697-704).

In a study presented at this year’s World Transplant Congress in San Francisco, Uday S. Nori, MD, and colleagues at The Ohio State University Wexner Medical Center in Columbus found that hypertension, glucose intolerance, and high body mass index accounted for 60% of all medical deferrals.

At last year’s American Transplant Congress in Seattle, Zoe A. Stewart, MD, PhD, of the University of Iowa Hospitals and Clinics in Iowa City, presented findings of a study involving 450 living kidney donor candidates, of whom 398 were rejected for donation and 52 were approved.

Rejected candidates had a mean BMI of 28.9 kg/m2, which was significantly higher than the mean 25.9 kg/m2 for the approved group. Of candidates approved for donation, only 11.5% were obese (BMI above 30) and 88.5% were non-obese (BMI below 30).

Heidi M. Schaefer, MD, a nephrologist and an associate professor of medicine at Vanderbilt University School of Medicine in Nashville, Tenn., noted that her institution’s transplant center turns down about 40% of potential living kidney donors for medical reasons.

“We have become more stringent over the past 10 years, in particular with 24-hour urine protein cutoffs and blood glucose cutoffs,” said Dr. Schaefer, who also is a TAG member. In addition, the center is seeing larger numbers of older and marginal donors. “Both factors are probably contributing to our inability to increase our living donor pool at our institution,” Dr. Schaefer said.