478 Effect of recipient age Age has an important influence on the transplant as well on as patient survival. Until recently, young age was consid- ered to be the most important predictor of outcome: the United Network for Organ Sharing (UNOS) has shown graft survival of 71% and 60% at 1 year and 5 years in those under the age of 2 years at transplantation, 83% and 64% in those aged 3 to 12 years and 85% and 57% in those aged 13 to 21 years [44]. Others have reported similar values for under fives of 67.7% at 1 year, 57.4% at 5 years and 45.2% at 10 years [30]. UK Transplant demonstrated increased risk of early transplant loss, principally due to technical difficulties, in those under 2 years of age, although after this age risk was equal to that in older children [22]. More recent UNOS data has shown that younger age and earlier era of transplantation adversely affect transplant outcome and gave an odds ratio of 2 for increased risk of graft loss in 2 to 5 year olds in comparison with 6 to 12 year olds [42]. However, in the past decade, the effect of young age has become less, such that children under 10 years of age now have the best long-term graft and patient survival rates of all recipients [1, 18]. Causes of graft loss are different in the youngest children, when surgical issues such as venous and arterial thromboses and urological problems predominate. This means that the large proportion of transplant loss is in the first few months after transplantation at this age [20]. Age becomes important again in adolescents, who, as a group, have the worst graft survival rate of all ages [18, 22, 40, 45]. Adolescents have a high percentage of late acute rejection episodes and relatively poor rejection reversal outcomes, compared to the other age groups, suggesting that lack of compliance with immunosuppressive regimens may be an important contributory factor [45]. Non- concordance contributes significantly to transplant loss at this age [22, 46]. However, not only non-concordance may account for the increased graft loss: adolescents have a relatively high incidence of focal segmental glomeruloscle- rosis (FSGS) (12.3% of causes of ESRF), with decreased graft survival, compared to younger children with FSGS [47]. Effect of donor age Kidneys from deceased donors aged 11–17 years do best, with a 73% 5-year survival rate [18]. Some studies have warned of the increased risk of graft thrombosis in young patients when young donors, particularly under 5 years of age, are used [22, 25], although others have reported equal outcome, with transplant survival of 55% after 5 years, for donors <6 years of age, and of 60% for donors over that age [48], suggesting that the restriction of kidney selection to donors aged >6 years may not be justified. The Italian Pediatr Nephrol (2009) 24:475–484 registry suggests a lower cut-off age of 24 months [31]. More recently, the 5-year graft survival rate from donors <1 year of age has risen to 60% (equal to that of donors aged >50 years of age) and to 70% for donors aged 1 year to 5 years [18]. Therefore, it may be that the use of small kidneys is appropriate in selected patients. Effect of donor type Living related donation (LRD) has been shown to benefit outcome, with results of 75% and 85% at 10 years, compared to 46% for DDs [12, 49]. Belgian data showed 10% better transplant survival over DD kidneys [21]. Others have shown a benefit of LRD kidneys in the first 5 years after transplantation, although this benefit was lost by 10 years [1]. Possible explanations for this are that non- concordance and the effects of calcineurin inhibitor-induced nephrotoxicity have taken effect by this time and affect recipients of LRD kidneys equally with those receiving DD kidneys. It has been calculated that a 10-year-old child who received a renal transplant in 2000 and is receiving ciclosporin-based immunosuppression can expect a trans- plant half-life of 13.1 years from an LRD and 10.8 years from a DD [1], although for LD recipients with no acute rejection episodes, half-life has been calculated to be as high as 37.6 years [49]. LRD is of particular benefit to the recipient under 2 years of age. Five-year graft survival for recipients under 2 years old was 86% following LRD and 38% following DD transplantation. Recipients aged between 2 and 18 years over the same time period had a 5-year graft survival rate of 73% following LRD, which was similar to that for recipients less than 2 years of age in this study [20]. Effect of pre-emptive transplant NAPRTCS data show that transplant survival is improved in patients receiving a pre-emptive transplant compared with those undergoing PD and HD. Graft loss resulting from vascular thrombosis is more common in children who undergo PD than in those who on HD [50]. Eurotransplant found a difference in graft survival between those not on dialysis and those on dialysis of 82% and 69%, respective- ly, at 6 years [40]. It has been postulated that the delaying of transplantation in adolescents may lead to improved adherence, but this is at the cost of longer time on dialysis. The Australia and New Zealand Dialysis and Transplant Registry (ANZ- DATA) confirmed that 5- and 10-year graft survival rates were significantly worse in adolescents (65% and 50%, respectively) than in recipients aged 2 to 10 years (74% and 58%) and 20 to 29 years (72% and 57%). However, waiting time on dialysis was an independent risk factor for failure