Secondary immune thrombocytopenia (ITP) is a heterogeneous and unpredictable disease associated with various underlying conditions.
The objective of the study was to investigate clinical evolution and chronicity predictors in secondary ITP.
Patients treated at an academic medical center during 2008-2019 were stratified by age as children <16 years and adults <16 years. Responses to steroids, intravenous immunoglobulin G (IVIG), rituximab, and eltrombopag were classified as response (R) and complete response (CR). Risk factors for chronic ITP were determined by multiple regression with uni- and multi-variate analysis.
Eighty-three patients were included, 37 children and 46 adults. The most frequent associated conditions were infections 53%, systemic lupus erythematosus (SLE) 24%, thyroid disease 9.6%, and Evans syndrome 3.6%. Response to first-line treatment in the whole cohort was 94%; CR 45.7%; and R 50.6%. Initial response to steroids alone was 91.3% (n = 21/23), rituximab plus high-dose dexamethasone (HDD) 93.3% (n = 14/15); children receiving IVIG alone 100% (n=12/12); and eltrombopag in adults 100% (n = 3/3). Relapse was documented in 19.4% of children and 34% of adults, at a median time of 15 and 2 months, respectively; 30.4% of adults (15.2% from the miscellaneous group, 10.9% SLE-associated, and 4.3% infection-associated) and 18.9% of children followed a chronic course; age ≥10 years and platelets ≥20 × 109/L were risk factors for chronic ITP in children.
Evolution was heterogeneous: a better and more sustained response was documented in the infections group compared to SLE or the miscellaneous group.

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