BACKGROUND: The long-term outcome of primary immune thrombocytopenia (ITP) is unpredictable. Chronic ITP is common in adults, requiring second-line treatments with increased morbidity and mortality. Our study aimed to identify predictive factors of chronicity at the time of diagnosis in primary adult ITP.

METHODS: This retrospective multicenter study included adult patients newly diagnosed with primary ITP. Patients with a normal platelet count and no ongoing medication twelve months after disease onset were categorized in the complete remission ITP group, otherwise in the chronic ITP group.

RESULTS: 219 patients were included, 110 in the complete remission ITP group and 109 in the chronic ITP group. In multivariate analysis, predictive factors of progression to chronicity included the absence of an infectious event preceding ITP onset (p=0.048), the absence of bleeding manifestations (p=0.002) and a platelet count > 10 x 109/L at disease onset (p=0.02). A poor response to initial corticosteroid treatment was also associated with chronicity, including corticosteroid dependence (p<0.001) and corticosteroid resistance (p=0.001).

CONCLUSIONS: In this retrospective French cohort, predictors of chronicity in newly diagnosed primary adult ITP included the absence of preceding infectious event, platelet > 10 x 109/L and absence of bleeding manifestations at onset.