Risk factors and disease trajectories of recurrent immune thrombocytopenia in children.

This retrospective study aimed to analyse the course and outcome of recurrent immune thrombocytopenia (ITP) in children and to identify factors associated with recurrence. A total of 497 newly diagnosed ITP children with platelet <30 × 10⁹/L between January 1988 and December 2019 were included. Recurrent ITP was defined as a new event of thrombocytopenia after at least 3 months of remission without treatment. Twenty-nine (5.8%) children experienced 48 recurrent episodes. The median time from diagnosis to recurrence was 22 months. Most recurrences occurred in children aged 1.5-10 years with a recent infection history. Compared to non-recurrent ITP, children with recurrent ITP had delayed remission with lower platelets at 1 month and 3 months postdiagnosis. Multivariate analysis identified aged 1.5-10 years (hazard ratio [HR] 3.65, 95% confidence interval [CI]: 1.35-9.82) and delayed remission at 7-12 months (HR 4.04, 95% CI: 1.37-11.95) as predictors for recurrence. Most recurrent ITP patients had minor or mild symptoms, higher platelet counts, did not require treatment, and achieved remission within 12 months. The similar remission trajectories among the first and recurrent ITP, but different from the courses in the non-recurrent ITP, suggest that recurrent ITP might have a unique biological basis.