Characteristics, management and outcomes of atypical haemolytic uraemic syndrome in kidney transplant patients: a retrospective national study.

Background: Kidney transplantation (KTx) is a strong trigger for the development of either recurrent or atypical haemolytic uraemic syndrome (aHUS). According to previous studies, eculizumab (ECU) is effective for prophylaxis and for treatment of recurrence.

Methods: We evaluated the experiences of Spanish patients with recurrent and aHUS associated with KTx, treated or not treated with ECU. In the group, we classified patients as having early (during the first month) or late aHUS (subsequent onset).

Results: We analysed 36 cases of aHUS associated with KTx. All of the 14 patients with pre-KTx diagnosis of aHUS were considered to have high or moderate risk of recurrence. Despite receiving grafts from suboptimal donors, prophylactic ECU was effective for avoiding recurrence. The drug was stopped only in two cases with low-moderate risk of recurrence and was maintained in high-risk patients with no single relapse. There were 22 aHUS cases and 16 belonged to the early group. The median time of onset in the late group was 3.4 years. The early group had a better response to ECU than the late group, probably due to earlier diagnosis and use of the drug. No genetic pathogenic variant was detected in aHUS cases, suggesting a secondary profile of the disease. ECU was stopped in all patients with no relapses. ECU was well tolerated in all cases.

Conclusions: Both groups (pre-aHUS and ) presented different clinical profiles, management approaches and outcomes. One should consider aHUS regardless of time after KTx. Genetic studies are crucial to stratify risks of relapse and to determine necessary lengths of treatment. We suggest short ECU treatment for cases without pathogenic mutation and that ECU treatment be considered pre-emptively for patients with moderate or high risk of recurrence.