Immune Thrombocytopenia in Finnish Children and Adolescents: A Population-Based Cohort Study

Aim: Immune thrombocytopenia (ITP) is the most common cause of thrombocytopenia in children. This study aimed to describe the diagnostics, patient characteristics, and treatment strategies regarding children with ITP, as well as identify risk factors for chronic disease. Methods: This study included 403 Finnish children aged under 16 years at diagnosis, who were first diagnosed with ITP between 2006 and 2020. Results: Of the 367/403 patients with complete follow-up data, 242 (65.9%) recovered within three months. Chronic ITP developed in 25.9% of the children. Severe bleeding events occurred in 3.7% of them, with no intracranial bleeding events or deaths reported. Pharmacological treatment was administered to 40.2% of the patients. An elevated risk of chronic ITP was found in the children presenting with an insidious disease onset, female gender, higher age, higher platelet counts, and an absence of recent viral infections. As many as 83.3% of the patients with an insidious disease onset and no recent infections developed chronic ITP. Conclusion: Most of the children with ITP experienced short and uncomplicated disease courses. Chronic illness was more likely when the disease onset was insidious, the platelet count was not extremely low, and there was no recent history of an infection.