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

Summary 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) 3·23, 95% confidence interval (CI) 2·26–4·61], exposure to corticosteroids (HR 3·55, 95% CI 2·74–4·58), thrombopoietin‐receptor agonists (TPO‐RAs; HR 2·28, 95% CI 1·59–3·26) and intravenous immunoglobulin (IVIg; HR 2·10, 95% CI 1·43–3·06). A higher risk of hospitalisation for AT was observed with older age, male sex, a history of cardiovascular disease, splenectomy (HR 1·50, 95% CI 1·12–2·03), exposure to IVIg (HR 1·85, 95% CI 1·36–2·52) and TPO‐RAs (HR 1·64, 95% CI 1·26–2·13). 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.