Accumulation of elderly ESRD patients with blood group O on the waiting list

End stage renal disease is associated with high morbidity and mortality which increase with age. It has been shown that renal transplantation improves live expectancy even in elderly patients [1]. The Eurotransplant Senior Program (ESP) was implemented on 1.1.1999 to meet the needs of an aging society. Other aspects of this program are an increasing number of organ offers from elderly deceased donors (organs, which may lead to inferior outcomes of the recipients when grafted onto young patients [2]), a shorter life expectancy of elderly patients (which makes it logical to allocate organs with a similar short life expectancy to these patients – ‘functional match’), and attempts to expand the deceased donor pool to prevent a further increase in waiting times. In their 5 years analysis of the ESP, Frei et al. found that graft and patient survival were not negatively affected and concluded that age matching of elderly donors and recipients is an effective allocation system [3]. ESP-allocation does not use human leukocyte antigen (HLA) matching but tries to keep cold ischemia time as short as possible [4]. Therefore, organs from donors aged ‡65 years are allocated to recipients aged ‡65 years within a narrow geographic region only by waiting time. According to ESP-blood group rules, kidneys have been allocated to elderly recipients as follows: A to A or AB, B to B or AB, AB to AB and O to O or B. In contrast to other countries, in Germany O-ESPkidneys have been allocated to O), A), B) and AB-recipients [5], which allowed for a substantial transfer of O-kidneys to other blood groups. This contrast and the results of our analysis on the ‘blood group O problem’, in the regular Eurotransplant kidney allocation (ETKAS) [6] led us to investigate blood group specific differences in ESP-allocation in our center. We performed a retrospective single center analysis using data from a web-based patient record system, TBase [7]. Data were retrieved from all elderly patients awaiting a first kidney graft at the age ‡65 years starting by the 1st of January 1999. End of observation was the 31st of December 2009 (waiting list) and 31st of December 2010 (follow-up). ‘Pure’ ESP-patients with start of renal replacement therapy (RRT) at ‡65 years and combined ETKAS/ESP-patients (start of RRT <65) were differentiated for the calculation of waiting times. Endpoints were removal from or death on the waiting list and transplantation. Frequencies were compared using the chi-square test. Numerical values were tested by t-test. A P-value of less than 0.05 was considered to be statistically significant. Between 1999 and 2009, 297 patients have been waitlisted in our center for first KTX within ESP. A total of 190 patients received a first kidney graft (seven with a living donor). Significantly, more patients died on the waitlist than after KTX (annual mortality rate 8.6 vs. 4.0 cases per 100 patient years, respectively, Log Rank: P < 0.00001). The analysis of outcomes on the waiting list revealed that O-patients had a significantly higher rate of removal (38/ 128, 29.7% vs. 25/169, 14.8% in non-O-patients, P = 0.002) and a highly significant lower chance of KTX (58/128, 45.3% vs. 132/169, 78.1% in non-O-patients, P < 0.001). Next we analyzed waiting times from all 190 KTX. Patients who accumulated waiting time before reaching the ESP (65th birthday) had longer waiting times (57.1 ± 22.1 months for O-patients vs. 50.3 ± 22.4 months in non-O-patients, P = 0.12) than patients with start of RRT at age ‡65 (40.5 ± 26.1 months [O] vs. 24.3 ± 12.7 months [non-O], P < 0.001). Furthermore, we observed a highly significant lower rate of transplantation in O-patients with start of RRT ‡65 compared with patients with start of RRT <65 (17/58, 29.3% vs. 41/70, 58.6%, P < 0.001). The transplantation rate of non-Opatients was not dependent on the age at initiation of RRT. To investigate the reason for the longer waiting times for O-recipients, we investigated the ABO-non-identical allocation of deceased donor kidneys. The proportion of patients with blood group O was only slightly higher among waitlisted patients (128/297 – 43.1%) than in deceased donors (63/183 – 34.4%). However, patients with blood group O received only 30.1% of all kidneys (55/183). A number of kidneys were transferred from O), A) and B-donors to other (compatible) blood groups. This led to a ‘deficit’ of eight KTX in O-patients, whereas A-patients received in total +2, B-patients )1 and AB-patients +7 kidneys. As a result, at the end of the observation period, 72.7% of the remaining patients were non-grafted