Introduction: In Argentina, hemolytic uremic syndrome (HUS) is an endemic disease. It is the second most common cause of kidney transplantation (KTx) in children. Since several years, protective measures have been implemented to reduce kidney sequelae and to delay progression to end-stage renal disease (ESRD). The aim of this study was to determine whether the cumulative incidence of HUS in children undergoing KTx at a public hospital has decreased and if HUS continues being the second most common cause of ESRD in these patients.
Material and Methods: A retrospective cohort study was conducted including 1000 KTx performed at Hospital J.P. Garrahan between December 14, 1988, and August 18, 2021. The population of children who underwent KTx in this period was divided into quintiles and children with HUS were compared to those with ESRD related to other etiologies in each quintile, together with the time of KTx.
Results: Analyzing the cohort of children who underwent KTx in different quintiles, HUS continued being the second-most common reason for KTx in quintiles 1 (1988-1995), 2 (1996-2003) and 3 (2004 - 2009). In quintiles 4 (2010-2015) and 5 (2016-2021) HUS became the third cause. Focal and segmental glomerulosclerosis had become the second most common cause. Comparing the proportion of patients with HUS to those with other etiologies of ESRD in quintiles 1,2 and 3 vs quintiles 4 and 5 (in the latter of which HUS became the third cause of ESRD), this number decreased over time: 1st quintile:  17% (n=34/200; p: <0.001), 2nd quintile: 13.5% (n=27/200; p: 0.004), 3rd quintile: 11.5% (n=23/200; p: 0.03) and 4th and 5th quintile 10% (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 quintiles 1,2, and 3) cumulative incidence was 14% vs 6.45% in era 2 (quintiles 4 and 5; p: 0.0002). Mean decrease of the risk of requiring KTx because of HUS was 54% (95% CI: 30-70%; p:0.0002). In era 1, 84 patients had HUS and in era 2 26. 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). In none of the patients the disease recurred.
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.