Kidney Graft Survival Rates do not improve by era: the impact of factor “Age” E. Bertoni MD, A. Larti MD, G. Rosso MD and M. Salvadori MD Renal Unit – Careggi University Hospital – Florence - Italy

Background According registry data on kidney transplantation, graft survival rate improves because of rejection rate reduction (fig. 1), but may be impaired by the increasing number of old donors and recipients.

Fig. 1 Graft survival according transplant year. CTS Data

Aim of the Study As the age of both donors and recipients dramatically increased in our country, aim of this study was to verify in our center how the graft survival rate changed by era.

Patients and Methods I We compared both the 5-year actual graft survival rate and the 5-year death- censored graft survival rate of 89 recipients transplanted in (period A) with 221 recipients transplanted in (period B). As in period B we adopted new immunosuppressants as MMF, Neoral and IL2R inhibitors, an improvement in graft survival was expected.

Patients and Methods II The two period rejection rates and the incidence of donors and recipients > 50 years were considered. Kaplan-Meier estimates and Log-Rank test were performed by the Collaborative Transplant Study (CTS) whom our data had been regularly sent to.

Results I Period B 5-year graft survival rate was lower with respect to period A (76.3% vs 82%) (Fig. 2). The death censored graft survival rate was similar ( 87.1% vs 87.5%) (fig. 3). The period B acute rejection incidence was 18% vs 40% of period A (p< 0.001).

Fig. 2 Graft survival by transplant year

Fig. 3 Death censored graft survival by transplant year

Results II Both overall donor and recipient age had the highest impact on 5-year graft survival rate: for donor age years 86.2% vs 65.7% for donor age >50years (p<0.0001) (fig. 4). Similar effect was observed for recipient age: 84.1% for age years vs 68% for age > 50 years (p = ) (fig.5).

Fig. 4 Graft survival by donor age Log Rank Test p =

Fig.5 Graft survival by recipient age Log Rank Test p =

Results III In period A donors > 50 years were 23.6% vs 50.2% in period B (p 50 years were 35.9% vs 42.9% in period B (p>0.01). This justifies the overall worse outcome of period B. Indeed comparing donor and recipients with similar age we observed an improvement of 5-year graft survival rate (figg. 6,7). Censoring for death with function such improvement becomes significant (figg.8,9)

Conclusions Kidney graft survival rate of patients transplanted in was higher with respect to These data disagree with the survival rates expected by the reduction of 1- year rejection rate due to new immunosuppressants Expanded donor criteria can account for such discrepancy. Indeed in period B we had more donors and recipients over 50 years. Most of graft failure were due to death with function, but also a poorer quality of kidneys accounts for this phenomenon. Indeed looking for graft survival rate of patients under 50 years we observed an improvement as expected.