The Impact of Morbidity and Mortality of Live Kidney Donation
Perioperative Mortality and Long-term Survival Following Live Kidney Donation
Segev DL, Muzaale AD, Caffo BS, et al
Segev and colleagues retrospectively examined the United Network for Organ Sharing (UNOS) registry and identified 80,347 live donor kidney transplants occurring in the United States between April 1, 1994, and March 31, 2009. A matched cohort was drawn from 9364 nondonor participants in the third National Health and Nutrition Examination Survey (NHANES III), after excluding those with contraindications to live kidney donation. Mortality rates were confirmed by linking patients to the Social Security Death Master File. During the 15-year period of study, the number of live donor kidney transplants performed annually increased significantly (from 3009 in 1994 to 5968 in 2008). Donor age increased over time, with 13.9% of donors being older than 50 years in 1994 compared with 22.8% in 2008. A total of 58,683 (73.1%) live kidney donors were white, 10,505 (13.1%) were black, and 9846 (12.3%) were Hispanic. For donors after 2003, 22.6% were classified as obese (body mass index [BMI] ≥ 30 kg/m), and 1.8% had hypertension.
The risk for death in the first 90 days following live donor nephrectomy (defined, for purposes of the study, as surgical mortality) was 3.1 per 10,000 donors compared with 0.4 per 10,000 (P < .001) in the matched cohort. By the time of the 1-year follow-up, the risk for death in the donor group and the matched cohort was similar (6.5 per 10,000 donors post-nephrectomy versus 4.6 per 10,000 in the matched cohort, P = .11). During the 15-year study period, surgical mortality did not change among live donors despite differences in practice and selection. Men, blacks, and donors with hypertension had significantly higher surgical mortality rates, whereas no significant differences were noted for age, smoking status, BMI, or systolic blood pressure.
Long-term survival was influenced by older age, male sex, black race, higher systolic blood pressure, and smoking. However, long-term risk for death was not higher for live donors than for NHANES III participants matched for age and comorbidity. On the basis of these findings, the investigators concluded that mortality was not increased after a median follow-up of 6.3 years among a cohort of live kidney donors as compared with a healthy, matched cohort.
UNOS began collecting data in 1988. The number of live donor kidney transplants performed annually in the United States steadily increased to a peak of 6647 in 2004, after which the numbers dropped for the next 4 years before rebounding to a total of 6387 in 2009. The field of live donor transplantation has expanded in recent years to include not only related donors but unrelated donors, paired donor exchanges, anonymous altruistic donors, older donors, donors with single-drug hypertension, obese donors, and intentional blood type or crossmatch incompatible transplants. Kidney transplantation from a living, healthy donor who has normal renal function provides numerous advantages over other types of renal transplantation, including the absence of derangements related to brain death, minimization of cold ischemia, and the opportunity for preemptive (or at least scheduled) transplantation. For these reasons, live donor transplantation remains the single best way for patients with end stage renal disease to receive a kidney.
The seminal article by Segev and colleagues reports one of the largest and most comprehensive studies to date that examines short- and long-term survival outcomes following live donor nephrectomy. Overall, studies of former kidney donors have revealed excellent long-term outcomes, with respect to donor health, when compared with the general population. However, previous studies had important limitations that precluded an extrapolation of the results to all populations. Most studies that have evaluated live kidney donors were conducted at single academic centers and involved carefully selected and primarily younger white donors, and in most of these studies follow-up was sporadic. Outcomes associated with older kidney donors and various racial/ethnic minority groups, many of whom bear a disproportionate burden of kidney disease, have not been described in detail, and preliminary studies have yielded conflicting results. Chronic kidney disease tends to be more prevalent and to progress more rapidly in certain ethnic groups. In addition, it is well established that nephron mass, overall kidney function, and the capacity for compensatory hypertrophy decline with age. Moreover, the influence of mild hypertension and obesity remains uncertain when evaluating prospective candidates for kidney donation.
This study provides a large and diverse sample size that begins to delineate the risks associated with live kidney donation in all racial/ethnic and age groups and confirms the safety of the live donor nephrectomy procedure as practiced in the United States.
This study also raises broader healthcare issues. All kidney donors, but particularly those from higher risk populations, would benefit from long-term medical follow-up. Discrimination from insurance companies as a result of kidney donation may result in curtailed access to healthcare and a delay in recognition of treatable health problems such as hypertension. It is appropriate to protect the insurability of donors and provide adequate medical and social follow-up after kidney donation, given the heroic and voluntary nature of the donation process.