Living Kidney Donors: Current State of Affairs
2009; Elsevier BV; Volume: 16; Issue: 4 Linguagem: Inglês
10.1053/j.ackd.2009.05.007
ISSN1548-5609
Autores Tópico(s)Organ Transplantation Techniques and Outcomes
ResumoLiving kidney donation continues as the cornerstone of transplantation. In order to determine with ever-renewing assurance that living donation is safe for the donor, we need to periodically review the literature, review the United Network for Organ Sharing database for donor characteristics that may put them in danger, and scour databases for donors starting dialysis and/or listed for transplant. Additionally, we must encourage financing studies that follow large diverse cohorts of donors over their entire lifetimes in order to detect key characteristics that influence outcomes. Currently, it can be stated that living donation is, on the whole, safe, with few perioperative deaths, complications, or long-term medical issues. Additionally, the living donor reflects the demographics of the general population including increased rates of obesity with some donors having hypertension and low-grade proteinuria. In the long run, death rates (for the white donor) are no different than for the general population, whereas end-stage renal disease rates are slightly increased over the general population, ranging from 0.1% to 1.1%. The higher risk is especially notable in the black donor. Preeclampsia in female donors may also be marginally greater than in those with 2 kidneys. Thus, the new health age brings a rejuvenated responsibility of the medical community and those in governance to design systems that allow more complete and continued follow-up of the living kidney donor, especially those of color. Living kidney donation continues as the cornerstone of transplantation. In order to determine with ever-renewing assurance that living donation is safe for the donor, we need to periodically review the literature, review the United Network for Organ Sharing database for donor characteristics that may put them in danger, and scour databases for donors starting dialysis and/or listed for transplant. Additionally, we must encourage financing studies that follow large diverse cohorts of donors over their entire lifetimes in order to detect key characteristics that influence outcomes. Currently, it can be stated that living donation is, on the whole, safe, with few perioperative deaths, complications, or long-term medical issues. Additionally, the living donor reflects the demographics of the general population including increased rates of obesity with some donors having hypertension and low-grade proteinuria. In the long run, death rates (for the white donor) are no different than for the general population, whereas end-stage renal disease rates are slightly increased over the general population, ranging from 0.1% to 1.1%. The higher risk is especially notable in the black donor. Preeclampsia in female donors may also be marginally greater than in those with 2 kidneys. Thus, the new health age brings a rejuvenated responsibility of the medical community and those in governance to design systems that allow more complete and continued follow-up of the living kidney donor, especially those of color. Living kidney donation is at center stage in the treatment paradigm for patients with end-stage renal disease (ESRD) (Fig 1). Also, attracting the spotlight is the concern over the long-term consequences of living donation even though they are extensively evaluated and highly selected to be healthy at the time of donation. This article reviews what is known to date about the hard outcomes of death, postoperative complications, and ESRD in living donors. In addition, donors' current demographics and physical condition will be described, after which several policy issues are discussed. The anticipated changes in donor risk must be placed into context with the donor's willingness to provide benefit to their recipient. Furthermore, we need to assess the donor in the context of our changing society and changing risks for developing chronic disease, while continuing to investigate their risk of adverse outcomes in the setting of contemporary medical realities such as obesity, diabetes, and a lack of access to health care. Death after living donation is quite rare, with the risk of death reported as 0.02% to 0.04% within 90 days of donation.1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar, 3Matas A.J. Bartlett S.T. Leichtman A.B. et al.Morbidity and mortality after living kidney donation: 1999-2001 survey of United States transplant centers.Am J Transplant. 2003; 3: 830-834PubMed Google Scholar From the initiation of the United Network for Organ Sharing (UNOS) tracking of donor deaths in October 1999 through December 2007, 14 living kidney donor deaths (out of 51,153 donors, 0.03%) that occurred within 30 days of donation were reported to UNOS or identified by examination of the Social Security Death Master File.1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar In 2008, 1 further death was reported. During the same time period (October 1999 to December 2007), 39 of 51,153 (0.08%) donors had died by 12 months after donation. Organ Procurement and Transplantation Network (OPTN)/United Network for Organ Sharing (UNOS) and Social Security Death Master File data on donor death beyond the postoperative period suggest the same pattern as in the general population.1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar The most common reasons for death at any time (range = 0-2688 days) (N = 154 for the cohort, plus 1 donor whose cause of death is recorded as predonation coma) are listed in Table 1. Even though donors reportedly undergo a thorough evaluation before donation, some causes of death (eg, myocardial infarction, cancer, suicide, and homicide) within a short time after donation point to a need for programs to review their donor outcomes in the context of their program's predonation medical and psychosocial evaluations. Even within a highly selected population, complications will occur, and the question remains as to whether even more of such complications are preventable?Table 1Causes of Death in Living Kidney Donors From October 1999 to December 2007 (N = 154)1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google ScholarCause of DeathPercent of DeathsCancer11.6MVA7.1Cardiovascular disease7.1Accidental other than MVA5.2Homicide3.9Suicide3.2Hemorrhage1.9Respiratory failure1.9Other pulmonary1.9Infection1.9Neurologic1.9Pancreatitis0.6Unknown51.6Abbreviation: MVA, motor vehicle accident. Open table in a new tab Abbreviation: MVA, motor vehicle accident. Acute postoperative complications reported by programs to UNOS generally include bleeding, gastrointestinal injury and/or malfunction, venous thromboembolism, and reoperation.2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar Analyses of short-term (6 weeks after donation) outcomes for living kidney donors in the OPTN/UNOS data have found that 3.9% of the living kidney donors who donated in 2005 and 2006 (N = 13,006), had at least 1 adverse event. The most common events including reoperation are enumerated in Table 2. The most common reasons for reoperation were bleeding (n = 25), bowel obstruction (n = 8), and hernia repair (n = 7). The most common reason for donor readmission was an abdominal problem (n = 105; eg, nausea, vomiting, gastroenteritis, abdominal pain, ileus, constipation, or bowel obstruction). Less frequent reasons included chylous ascites, pancreatitis, shortness of breath, pulmonary embolism, subphrenic fluid, and infection (eg, wound, pneumonia, or urinary tract). Because over 50% of Living Donor Registration forms were submitted by transplant centers less than 6 weeks after donation, these data are all considered minimum estimates. Higher complications rates have been reported when donors themselves are the reporter.4McCune T.R. Armata T. Mendez-Picon G. et al.The Living Organ Donor Network: A model registry for living kidney donors.Clin Transplant. 2004; 18 (suppl 12): 33-38Crossref PubMed Scopus (24) Google ScholarTable 2Postoperative Complications Reported by Centers to the UNOS for Living Kidney DonorsComplicationPercentReadmission1.7Interventional procedure0.6Reoperation0.5Blood transfusion0.5Vascular complication0.3Other2.1NOTE. Frequencies of complications from kidney donors who donated during years 2005 and 2006 are shown (N = 13,006).1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar Open table in a new tab NOTE. Frequencies of complications from kidney donors who donated during years 2005 and 2006 are shown (N = 13,006).1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 2Wainright J. Cooper M. Bolton L. et al.Short-term complications of living donation.Am J Transplant. 2008; 8: 282Google Scholar By inulin clearance determinations of the glomerular filtration rate (GFR) and para-aminohippuric acid determinations of effective renal plasma flow, we know that the average decrease in overall GFR after donation is 20% to 30% (69/104) and for renal plasma flow it is 30% to 40% (349/536).5Rook M. Bosma R.J. Van Son W.J. et al.Nephrectomy elicits impact of age and BMI on renal hemodynamics: Lower postdonation reserve capacity in older or overweight kidney donors.Am J Transplant. 2008; 8: 2077-2085Crossref PubMed Scopus (71) Google Scholar This is at the expense of hyperfiltration in the remaining kidney.6Sobh M. Nabeeh A. el-Din A.S. et al.Long-term follow-up of the remaining kidney in living related kidney donors.Int Urol Nephrol. 1989; 21: 547-553Crossref PubMed Scopus (20) Google Scholar The absolute ability to increase GFR is dependent on age and obesity. Obese young donors do not retain the ability to fully compensate for the loss or renal, and, although older donors do increase single kidney GFR, the absolute increase is comparatively less.5Rook M. Bosma R.J. Van Son W.J. et al.Nephrectomy elicits impact of age and BMI on renal hemodynamics: Lower postdonation reserve capacity in older or overweight kidney donors.Am J Transplant. 2008; 8: 2077-2085Crossref PubMed Scopus (71) Google Scholar Many young women consider living donation before completing their childbearing. The classical teaching from a prior survey was that pregnancy was not negatively impacted by a previous unilateral nephrectomy.7Wrenshall L.E. McHugh L. Felton P. et al.Pregnancy after donor nephrectomy.Transplantation. 1996; 62: 1934-1936Crossref PubMed Scopus (36) Google Scholar However, researchers in Norway who linked data from birth records and the living donor registry discovered that women who donated (N = 306 donors: 726 pregnancies, with 106 pregnancies after donation) had a higher rate of preeclampsia after donation (5.7%) in comparison to the rate before donation (2.6%) and that of randomly chosen Norwegian birth registry controls (3.5%) at a ratio of 1,000:1.8Reisaeter A.V. Røislien J. Henriksen T. et al.Pregnancy and birth after kidney donation: The Norwegian experience.Am J Transplant. 2009; 9: 820-824Crossref PubMed Scopus (95) Google Scholar The differences were significant when comparing pre- versus postdonation pregnancies; when adjusted for maternal age and parity, the P value was <.001. There was also an insignificant increase in gestational hypertension after donation (1.8% of donors predonation, 2.8% of donors postdonation, 1.4% of controls).8Reisaeter A.V. Røislien J. Henriksen T. et al.Pregnancy and birth after kidney donation: The Norwegian experience.Am J Transplant. 2009; 9: 820-824Crossref PubMed Scopus (95) Google Scholar These findings are supported by a survey of female donors from the University of Minnesota who had pre-and/or post-donation pregnancies (n = 822 donors with 2,426 pregnancies before donation; n = 223 donors with 459 pregnancies after donation). In this survey, predonation preeclampsia was reported in 0.7% of pregnancies and postdonation in 5.2% (P < .0001), whereas gestational hypertension was noted in 0.4% predonation and in 4.4% (P < .0001) after donation.8Reisaeter A.V. Røislien J. Henriksen T. et al.Pregnancy and birth after kidney donation: The Norwegian experience.Am J Transplant. 2009; 9: 820-824Crossref PubMed Scopus (95) Google Scholar Additionally, gestational diabetes was reported in 0.7% before donation and 2.4% (P = .0004) after. Although this new information must be recognized for what it is, self-reported survey data without fixed criteria for the diagnosis of preeclampsia or hypertension, it provides an impetus for further investigation. An additional note of caution is due. These data are only valid in the white population because women of other racial and ethnic backgrounds were not included in either study. Long-term outcomes reported from single-center studies in largely white populations have revealed outcomes equal to or better than the general population.9Ibrahim H.N. Akkina S.K. Leister E. et al.Pregnancy outcomes after kidney donation.Am J Transplant. 2009; 9: 825-834Crossref PubMed Scopus (104) Google Scholar, 10Fehrman-Ekholm I. Elinder C.G. Stenbeck M. et al.Kidney donors live longer.Transplantation. 1997; 64: 976-978Crossref PubMed Scopus (327) Google Scholar, 11Najarian J.S. Chavers B.M. McHugh L.E. et al.20 years or more of follow-up of living kidney donors.Lancet. 1992; 340: 807-810Abstract PubMed Scopus (561) Google Scholar, 12Soneji N.D. Vyas J. Papalois V.E. Long-term donor outcomes after living kidney donation.Exp Clin Transplant. 2008; 6: 215-223PubMed Google Scholar, 13Fehrman-Ekholm I. Dunér F. Brink B. et al.No evidence of accelerated loss of kidney function in living kidney donors: Results from a cross-sectional follow-up.Transplantation. 2001; 72: 444-449Crossref PubMed Scopus (240) Google Scholar, 14Fehrman-Ekholm I. Brink B. Ericsson C. et al.Kidney donors don't regret: Follow-up of 370 donors in Stockholm since 1964.Transplantation. 2000; 69: 2067-2071Crossref PubMed Scopus (138) Google Scholar The newest information on long-term outcomes is again from 2 studies of whites, one from Minnesota and one from Toronto.15Ibrahim H.N. Foley R. Tan L. et al.Long-term consequences of kidney donation.N Engl J Med. 2009; 360: 459-469Crossref PubMed Scopus (816) Google Scholar, 16Roderick P.J. Atkins R.J. Smeeth L. et al.CKD and mortality risk in older people: A community-based population study in the United Kingdom.Am J Kidney Dis. 2009; 53: 950-960Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar Ibrahim et al15Ibrahim H.N. Foley R. Tan L. et al.Long-term consequences of kidney donation.N Engl J Med. 2009; 360: 459-469Crossref PubMed Scopus (816) Google Scholar studied their 3,698 kidney donors from1963 through 2007 for death and the development of ESRD. Mortality was comparable to the general population. The development of ESRD is discussed later. Additionally, GFR, proteinuria, blood pressure, quality of life, and general health status were assessed independently in 255 of the donors. Renal functional studies revealed that 85.5% of donors, at a mean of 12.9 ± 9.2 years after donation, had a GFR ≥60 mL/min/1.73 m2. Hypertension was noted in 32.15% and albuminuria in 12.7%. Older age and higher body mass index were associated with a GFR <60 mL/min/1.73 m2 and hypertension. A longer time period from the time of donation was associated with albuminuria. Most donors had quality of life scores greater than population norms. Notably, limitations of the study include an ethnically uniform population, the lack of a comparably medically evaluated control population, and the evaluation of only a proportion of the donor population. Even mild degrees of kidney insufficiency and albuminuria have been associated with increased risks for cardiovascular disease.17Garg A.X. Prasad G.V. Thiessen-Philbrook H.R. et al.Cardiovascular disease and hypertension risk in living kidney donors: an analysis of health administrative data in Ontario, Canada.Transplantation. 2008; 86: 399-406Crossref PubMed Scopus (111) Google Scholar Given this association, concern for increased cardiovascular risk in living donors has been raised. However, Garg et al16Roderick P.J. Atkins R.J. Smeeth L. et al.CKD and mortality risk in older people: A community-based population study in the United Kingdom.Am J Kidney Dis. 2009; 53: 950-960Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar established that living donors did not have more cardiovascular events or die more often than the control population over 10 years (1.3% living donors v 1.7% controls). The investigators compared all of the living donors in Ontario, Canada, from 1993 through 2005 (N = 1,278) to (N = 6,359) controls matched for age, sex, income, and use of nonphysician health care.16Roderick P.J. Atkins R.J. Smeeth L. et al.CKD and mortality risk in older people: A community-based population study in the United Kingdom.Am J Kidney Dis. 2009; 53: 950-960Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar They did, however, report a significant increase in the number of living donors with hypertension (16.3%) compared with the control group (11.9%; hazard ratio = 1.4, confidence interval, 1.2-1.7). This is concordant with the data from a previous meta-analysis of long-term donor outcomes where by 10 years there was an average 5-mm Hg increase in donor blood pressure compared with age- and sex-matched controls.18Boudville N. Prasad G.V. Knoll G. et al.Meta-analysis: Risk for hypertension in living kidney donors. Donor Nephrectomy Outcomes Research (DONOR) Network.Ann Intern Med. 2006; 145: 185-196Crossref PubMed Scopus (312) Google Scholar In addition to classically "normal" donors who have been highly medically selected, it has recently been published that individuals with medical abnormalities are donating.19Reese P.P. Feldman H.I. McBride M.A. et al.Substantial variation in the acceptance of medically complex live kidney donors across US renal transplant centers.Am J Transplant. 2008; 8: 2062-2070Crossref PubMed Scopus (107) Google Scholar, 20Mandelbrot D.A. Pavlakis M. Danovitch G.M. et al.The medical evaluation of living kidney donors: A survey of US transplant centers.Am J Transplant. 2007; 7: 2333-2343Crossref PubMed Scopus (220) Google Scholar, 21Textor S.C. Taler S.J. Driscoll N. et al.Blood pressure and renal function after kidney donation from hypertensive living donors.Transplantation. 2004; 78: 276-282Crossref PubMed Scopus (145) Google Scholar, 22Heimbach J.K. Taler S.J. Prieto M. et al.Obesity in living kidney donors: Clinical characteristics and outcomes in the era of laparoscopic donor nephrectomy.Am J Transplant. 2005; 5: 1057-1064Crossref PubMed Scopus (131) Google Scholar The long-term risks to these donors are not yet well delineated. Medical issues in need of more study in the setting of kidney donation include but are not limited to renal artery stenosis, hypertension, morbid obesity, mild glucose intolerance, nephrolithiasis, and thin glomerular basement membranes.22Heimbach J.K. Taler S.J. Prieto M. et al.Obesity in living kidney donors: Clinical characteristics and outcomes in the era of laparoscopic donor nephrectomy.Am J Transplant. 2005; 5: 1057-1064Crossref PubMed Scopus (131) Google Scholar, 23Young A. Storsley L. Garg A.X. et al.Health outcomes for living kidney donors with isolated medical abnormalities: A systematic review.Am J Transplant. 2008; 8: 1878-1890Crossref PubMed Scopus (85) Google Scholar, 24Worcester E. Parks J.H. Josephson M.A. et al.Causes and consequences of kidney loss in patients with nephrolithiasis.Kidney Int. 2003; 64: 2204-2213Crossref PubMed Scopus (89) Google Scholar, 25Worcester E.M. Parks J.H. Evan A.P. et al.Renal function in patients with nephrolithiasis.J Urol. 2006; 176: 600-603Abstract Full Text Full Text PDF PubMed Scopus (93) Google Scholar, 26Gillen D.L. Worcester E.M. Coe F.L. Decreased renal function among adults with a history of nephrolithiasis: A study of NHANES III.Kidney Int. 2005; 67: 685-690Crossref PubMed Scopus (93) Google Scholar Recent research has found that between 0.1% and 1.1% of living donors have developed ESRD.15Ibrahim H.N. Foley R. Tan L. et al.Long-term consequences of kidney donation.N Engl J Med. 2009; 360: 459-469Crossref PubMed Scopus (816) Google Scholar, 27Gibney E.M. Parikh C.R. Garg A.X. Age, gender, race, and associations with kidney failure following living kidney donation.Transplant Proc. 2008; 40: 1337-1340Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar, 28Fehrman-Ekholm I. Nordén G. Lennerling A. et al.Incidence of end-stage renal disease among live kidney donors.Transplantation. 2006; 82: 1646-1648Crossref PubMed Scopus (131) Google Scholar, 29Pereira R.B. Scheeren J. Castro D. et al.Follow-up of kidney donors who developed uremia and went on the waiting list for a transplant: Should they have allocation priority?.Transplant Proc. 2008; 40: 1012-1013Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar, 30Gibney E.M. King A.L. Maluf D.G. et al.Living kidney donors requiring transplantation: Focus on African Americans.Transplantation. 2007; 84: 647-649Crossref PubMed Scopus (96) Google Scholar, 31Rosenblatt G.S. Nakamura N. Barry J.M. End-stage renal disease after kidney donation: a single-center experience.Transplant Proc. 2008; 40: 1315-1318Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar Follow-up of the 3,698 living donors from the University of Minnesota has revealed that 11 (0.29%) developed ESRD 22.5 ± 10.4 years after donation; 7 of the donors were women, and 8 were white.15Ibrahim H.N. Foley R. Tan L. et al.Long-term consequences of kidney donation.N Engl J Med. 2009; 360: 459-469Crossref PubMed Scopus (816) Google Scholar This roughly described an estimated incidence of ESRD in donors of 180 per million persons per year as compared with the overall adjusted incidence rate of 268 per million persons per year in the white population of the United States. More current analyses of the OPTN data by Cherikh et al32Cherikh WS, Pan-Yen F, Taranto SE, et al: Prior living kidney donors who were subsequently placed on the waiting list: An updated OPTN Analysis. 2008 American Transplant Congress (ATC), May 31 to June 04, 2008, Toronto, Ontario, CanadaGoogle Scholar revealed that 148 previous living kidney donors were on the kidney waiting list between January 1, 1996, and March 31, 2007. Most of the donors who were later listed for a kidney had donated between the ages of 18 and 34 and to a full sibling. Of special concern was their finding that the median time from donation to listing was 21 years for white donors and 16 years for black donors, implying that short-term follow-up of living donors may not adequately capture or quantify this risk. Also of worry was the finding that 43% of such donors were blacks who comprised and continue to compromise nearly 12% of living kidney donors. These data suggest that risks of postdonation ESRD are unequal among various ethnic/racial groups and mirror the increased risk of ERSD that these higher-risk groups experience within the general population.32Cherikh WS, Pan-Yen F, Taranto SE, et al: Prior living kidney donors who were subsequently placed on the waiting list: An updated OPTN Analysis. 2008 American Transplant Congress (ATC), May 31 to June 04, 2008, Toronto, Ontario, CanadaGoogle Scholar, 33McClellan W. Warnock D.G. McClure L. et al.Racial differences in the prevalence of chronic kidney disease among participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Cohort Study.J Am Soc Nephrol. 2006; 17: 1710-1715Crossref PubMed Scopus (131) Google Scholar, 34Hsu C.Y. Lin F. Vittinghoff E. et al.Racial differences in the progression from chronic renal insufficiency to end-stage renal disease in the United States.J Am Soc Nephrol. 2003; 14: 2902-2907Crossref PubMed Scopus (354) Google Scholar The most frequent reported causes of ESRD in living kidney donors after those categorized as "unknown" are glomerular diseases (primarily focal and segmental glomerulosclerosis), hypertensive nephrosclerosis, diabetes, and renovascular/other vascular diseases.1United Network for Organ Sharing, Richmond. VA data as of December 31, 2007. Available at: http://optn.transplant.hrsa.gov/policiesandbylaws2/policies/pdfs/policy_23.pdf. Accessed, May 11, 2009Google Scholar, 32Cherikh WS, Pan-Yen F, Taranto SE, et al: Prior living kidney donors who were subsequently placed on the waiting list: An updated OPTN Analysis. 2008 American Transplant Congress (ATC), May 31 to June 04, 2008, Toronto, Ontario, CanadaGoogle Scholar One recent study of black donors who had been recruited to return for evaluation after donation (between March 1996 and February 2002) at the University of Maryland disclosed that of the 39 of 107 black donors who returned, 41% had hypertension. Notably, it was unknown to the donor in 20.5% of cases.35Cooper M. Haririan A. Weir M. et al.Renal outcomes in African-American living kidney donors [abstract]. Poster presented at: XXII International Congress of the Transplant Society.Transplantation. 2008; 86: 303Crossref PubMed Google Scholar Furthermore 2.6% had diabetes. Microalbuminura was noted in 15.4% and macroalbuminuria in 2.6%. Chronic kidney disease was present in 17.9% using the Modification of Diet in Renal Disease Study 4 equation for staging. However, although it is known that estimated GFR equations do not perform well in living donor populations before or after donation,36Ibrahim H.N. Rogers T. Tello A. et al.The performance of three serum creatinine-based formulas in estimating GFR in former kidney donors.Am J Transplant. 2006; 6: 1479-1485Crossref PubMed Scopus (63) Google Scholar, 37Parasuraman R. Venkat K.K. Utility of estimated glomerular filtration rate in live kidney donation.Clin J Am Soc Nephrol. 2008; 3: 1608-1609Crossref PubMed Scopus (13) Google Scholar hypertension and other metabolic syndrome characteristics may be an explanation for the increased risk for ESRD in African American donors. Furthermore, the risk for focal and segmental glomerulosclerosis and hypertensive renal disease in blacks has recently been genetically linked to variations of the nonmuscle myosin heavy chain 9, which may foster alterations in intrarenal hemodynamics that are more pathophysiologically problematic in certain AA donors.5Rook M. Bosma R.J. Van Son W.J. et al.Nephrectomy elicits impact of age and BMI on renal hemodynamics: Lower postdonation reserve capacity in older or overweight kidney donors.Am J Transplant. 2008; 8: 2077-2085Crossref PubMed Scopus (71) Google Scholar, 38Kopp J.B. Smith M.W. Nelson G.W. et al.MYH9 is a major-effect risk gene for focal segmental glomerulosclerosis.Nat Genet. 2008; 40: 1175-1184Crossref PubMed Scopus (584) Google Scholar, 39Kao W.H. Klag M.J. Meoni L.A. et al.Family Investigation of Nephropathy and Diabetes Research Group. MYH9 is associated with nondiabetic end-stage renal disease in African Americans.Nat Genet. 2008; 40: 1185-1192Crossref PubMed Scopus (533) Google Scholar, 40Freedman B.I. Hicks P.J. Bostrom M.A. et al.Polymorphisms in the non-muscle myosin heavy chain 9 gene (MYH9) are strongly associated with end-stage renal disease historically attributed to hypertension in African Americans.Kidney Int. 2009; 75: 736-745Crossref PubMed Scopus (150) Google Scholar, 41Freedman B.I. Kopp J.B. Winkler C.A. et al.Polymorphisms in the nonmuscle myosin heavy chain 9 gene (MYH9) are associated with albuminuria in hypertensive African Americans: The HyperGEN Study.Am J Nephrol. 2009; 29: 626-632Crossref PubMed Scopus (66) Google Scholar Future investigations in living AA donors should include testing for such genotypic variation. Lastly, it should be noted that the data on donor ESRD do not include those who started dialysis but were not listed for transplant or those who died with ESRD but did not receive renal replacement therapy. A report of this analysis has finally been performed and is forthcoming. The relationship between living donors and their recipients has changed over time. Today, donors are less likely to be blood relatives (eg, parents and siblings) of the recipient and instead are spouses and friends. Another trend is the increased donation by adult offspring to their parents, increasing from 9% of living kidney donors in 1989 to 18.7% in 200
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