Risk factors of hospitalisation for thrombosis in adults with primary immune thrombocytopenia, including disease-specific treatments: a French nationwide cohort study

We aimed to assess the risk factors of venous thrombosis (VT) and arterial thrombosis (AT) in adults with primary immune thrombocytopenia (ITP), particularly in relation to treatments. The population comprised all incident primary ITP adults in France between 2009 and 2017 (FAITH cohort; NCT03429660) built in the national health database. Outcomes were the first hospitalisation for VT and AT. Multivariable Cox regression models included baseline risk factors, time-varying exposure to ITP drugs, splenectomy and to cardiovascular drugs. The cohort included 10 039 patients. A higher risk of hospitalisation for VT was observed with older age, history of VT, history of cancer, splenectomy [hazard ratio (HR) 3 center dot 23, 95% confidence interval (CI) 2 center dot 26-4 center dot 61], exposure to corticosteroids (HR 3 center dot 55, 95% CI 2 center dot 74-4 center dot 58), thrombopoietin-receptor agonists (TPO-RAs; HR 2 center dot 28, 95% CI 1 center dot 59-3 center dot 26) and intravenous immunoglobulin (IVIg; HR 2 center dot 10, 95% CI 1 center dot 43-3 center dot 06). A higher risk of hospitalisation for AT was observed with older age, male sex, a history of cardiovascular disease, splenectomy (HR 1 center dot 50, 95% CI 1 center dot 12-2 center dot 03), exposure to IVIg (HR 1 center dot 85, 95% CI 1 center dot 36-2 center dot 52) and TPO-RAs (HR 1 center dot 64, 95% CI 1 center dot 26-2 center dot 13). Rituximab was not associated with an increased risk. These findings help to estimate the risk of thrombosis in adult patients with ITP and to select treatment.