Introduction: In Argentina, hemolytic uremic syndrome (HUS) is an endemic disease. It is the second most common cause of kidney transplantation (KTx) in children. Although an improvement in sanitary conditions could reduce its incidence, this does not seem to occur in recent years. For more than three decades, protective measures have been introduced to reduce kidney sequelae and delay progression to end-stage renal disease (ESRD). If this were so, it should be reflected in a reduction in the cumulative incidence of KTx due to HUS. On the other hand, there is little information on the evolution of HUS in the post-transplant period compared to other etiologies of ESRD.

Aim:

1. To determine whether cumulative incidence of KTx in children with ESRD secondary to HUS has decreased over time in a series of 1000 transplants over 33 years, and if HUS continues to be the second cause of ESRD in these patients.
2. To compare patient and graft survival at the last follow-up visit in children transplanted for HUS.

Material and Methods: A retrospective cohort study was conducted including 1000 consecutive KTx performed at HospitalGarrahan between December 14, 1988 and August 18, 2021. All the cohort was divided into quintiles (Q), in each quintile cumulative incidence of HUS was compared to ESRD related to other etiologies. It was also analyzed in the different five-year periods of the transplant program. Patient and graft survival was compared to those with other etiologies of ESRD.

Results: Analyzing the cohort of children with KTx in different quintiles, HUS continued being the second-most common cause for KTx in Q1 (1988-1995), Q2 (1996-2003), and Q3 (2004 - 2009). In  Q4 (2010-2015) and Q5 (2016-2021) HUS became the third cause. Comparing the proportion of patients with HUS to those with other etiologies of ESRD in  Q1, Q2 and Q3 vs Q4 and Q5 this number decreased over time: Q1: 17% (n=34/200; p: <0.001), Q2: 13.5% (n=27/200; p: 0.004), Q3: 11.5% (n=23/200; p: 0.03) and Q4t and Q5 10.5% (n=20/200) and 3% (n=6/200), respectively. Cumulative incidence of patients undergoing KTx because of HUS was 10.97%. In era 1 (KTx performed in Q1, Q2 and Q3) cumulative incidence was 14% vs 6.45% in era 2 (Q4 and Q5; p: 0.0002). Mean decrease of the risk of requiring KTx because of HUS was 54% (95% CI: 30-70%; p:0.0002) No significant differences were found in age at dialysis initiation (8.9±4 vs 8 ±5 years; p=0.79) and at KTx (11±4 vs 12±5 years; p=0.188). Patient survival was not different between groups (p=0.15).  Graft survival in HUS vs CAKUT group was not different (p=0.61), but significantly better compared to those with KTx for FSGS (p: <0.001).

Conclusion: In this cohort, a decrease in cumulative incidence of KTx because of typical HUS was observed. This lower incidence may be due, at least in part, to measures to prevent ESRD. Graft survival was similar in HUS and CAKUT patients, but significantly better compared to those with FSGS.