New research indicates that age cut-offs for deceased organ donors prevent quality kidneys from being available to patients in need of life-saving transplants. Even kidneys from donors ≥80 years of age functioned for years after transplantation in a recent Clinical Journal of the American Society of Nephrology study.
“Nowadays, in many countries, about 30% to 60% of deceased kidney grafts are included in the so-called ‘extended criteria.’ However, as witnessed by the heterogeneity of organ discard rate across the transplant community, the limits of this policy are not well defined despite the development of several scoring systems,” the study authors wrote. They noted that donor age in particular represents a major reason for organ discard, but data on the reliability of organs from elderly donors are currently limited and relevant studies have generated conflicting results.
The donor organ shortage has led to recent efforts to find ways to expand kidney recovery criteria, however, including the consideration of older deceased donor kidneys. Strategies incorporating such kidneys include old for old protocols that aim to match the estimated graft survival to recipient life expectancy and dual kidney transplantation that is intended to compensate for the limited nephron mass of older donor kidneys.
To see how donor age affects the long-term functioning of transplanted kidneys, Luigi Biancone, MD, of the University of Torino, in Italy, and his colleagues retrospectively analyzed information on all deceased donor kidney transplants performed at the Turin University Renal Transplant Center over an 11-year period from 2003 through 2013, with kidney transplants from extended criteria donors classified according to donor age classes. In the first study specifically focusing on donors ≥80 years old and dividing extended criteria donor cohort into decades, the team assessed the most relevant long-term outcomes together with associated risk factors.
The investigators excluded multi-organ grafts from 1199 consecutive transplants. Of the remaining 1124, there were 647 kidney transplants from extended criteria donors, which were defined as all donors >60 years and those aged 50 to 59 years with ≥2 of the following characteristics: serum creatinine at procurement >1.5 mg/dL, cerebrovascular cause of death, and history of hypertension.
After a median follow-up of 4.9 years, patient and kidney survival rates were comparable among the 4 age groups considered (50–59 years, 60–69 years, 70–79 years, and ≥80 years). The 5-year patient survival rates ranged from 87.8% to 90.1% in these age groups, and the 5-year kidney survival rates ranged from 65.9% to 75.2%. Patient and graft survival rates were comparable between dual and single kidney transplants, except for the ≥80 year age group, which had better graft survival with dual kidney transplantation.
Donor age classes did not correlate with most adverse events, including vascular and urological complications, new onset diabetes, and malignancies. Acute rejection rates were also comparable in the 4 groups, whereas infection rates appeared to be lower in the ≥80 year age group, particularly for cytomegalovirus infection (11.1% vs. 26.4% of group 1, 31.8% of group 2, and 28.3% of group 3).
“The results of this study support the use of extended criteria donors, even donors older than 80 years, but they have to be accurately selected and managed with dedicated protocols,” Biancone said.
Rates of kidney discard before transplantation were similar for kidneys from donors in the 3 younger age groups (15.4%, 17.7%, and 20.1% respectively), but the discard rate was strikingly higher (48.2%) among kidneys from octogenarian donors. Most of the reasons for discard were age-related; in particular, macroscopic flaws and Karpinski score >6 were found in 20% and 11.8% of organs harvested from donors ≥80 years vs. 4.8% and 3.7% of those from the youngest extended criteria donors.
“Kidneys from octogenarian donors, which currently represent a significant proportion of the donor pool, are discarded in almost 100% of the cases by many transplant centers,” said Umberto Maggiore, MD, who was not involved with the study and is a transplant nephrologist at the University Hospital of Parma, in Italy.
“This study provides findings that might help transplant physicians for decision-making purposes,” Maggiore said. “I would summarize this with a simple rule of thumb, called the ‘half rule,’ as follows: using histological parameters (in this study a dedicated renal pathologist evaluated a formalin-fixed needle biopsy using the Karpinski score), half of the kidneys will be discarded; of those recovered, almost half of the donors will be eventually used for dual transplantation, the 5-year cumulative incidence of graft failure of those allocated to dual transplantation being half compared with single transplantation.”
Other evaluation tools—such as those that analyze vascular resistances and perfusate biomarkers during kidney machine reconditioning or donor urinary biomarkers for ischemia-reperfusion injury—may allow for an accurate allocation of organs from elderly donors.
The article, entitled “Long-term Outcomes and Discard Rate of Kidneys by Decade of Extended Criteria Donor Age,” appeared online at http://cjasn.asnjournals.org/ on December 15, 2016, doi: 10.2215/CJN.05990616.