To summarize the clinical data of atypical hemolytic uremic syndrome (aHUS) and analyze the treatment and prognosis.

A prospective cohort study was conducted on 66 cases in Beijing Children's Hospital affiliated to Capital Medical University from January 2011 to December 2017. The children were divided into positive and negative auto-antibody groups according to the results of anti-factor H autoantibody test. The clinical characteristics, treatment plan and prognosis of the two groups were compared.

Among the 66 children who met the inclusion criteria, there were 43 cases (65.2%) in the positive group, with an average onset age of(8.0±2.9) years. There were 23 cases (34.8%) in the negative group, with an average onset age of (3.0±2.6) years. On the basis of plasma treatment, in the positive group, the usage rate of hormone was 83.3%(35/42) and the usage rate of immunosuppressive agents was 42.9%(18/42), while in the negative group, the rates were 63.6%(14/22) and 13.6%(3/22) respectively. The average follow-up time was 19.3 months. One child in each group was lost to follow-up. In the positive group, 8 cases recurred (19.0%) and the average recurrence interval time was 16.1 months. In the negative group, 7 cases recurred (31.8%) and the average recurrence interval time was 9.3 months. And the recurrent interval time in the positive group was more longer than the negative group (P<0.05). A total of 85.9%(55/64) children had complete hemolysis control and complete recovery of renal function, in which the positive group was 85.7%(36/42) and negative group was 86.4%(19/22). However, 7.8%(5/64) children had abnormal renal function, in which the positive group was 9.5%(4/42) and the negative group was 4.5%(1/22). And 4.7%(3/64) children died, in which the positive group was 2.4%(1/42) and the negative group was 9.1%(2/22). The one left (1.6%) showed dialysis dependence, which was positive for the auto-antibody. Multifactor Cox regression analysis showed that the age of less than 3 years old was the risk factor of poor prognosis (HR=4.651, 95% CI 0.988-21.898, P=0.047).

The positive proportion of anti-factor H autoantibody in children with aHUS is high. The age of these children is older. Individualized therapy based on anti-factor H autoantibody and immunosuppressive therapy is of great significance for disease remission, preventing recurrence and improving the prognosis. Age less than 3 years old is the risk factor for poor prognosis.

Hemolytic-uremic syndrome; Immunosuppression; Prognosis; Complement Factor H; Plasma exchange