Cardiovascular and comorbid risk factors for thrombosis in primary immune thrombocytopenia: a single-center retrospective study.

Background: There is evidence that patients with immune thrombocytopenia (ITP) are at increased risk of thrombosis. The associations of clinical and comorbid factors with thrombosis in ITP remain unclear. Objectives: This study aimed to investigate the incidence rate and risk factors of arterial and venous thrombosis among patients with primary ITP. Methods: A retrospective cohort study was conducted, enrolling adult patients diagnosed with ITP at Qilu Hospital between January 1, 2014, and December 31, 2025. Thrombosis incidence was calculated using person-years of follow-up, and multivariable-adjusted Cox regression was used to identify independent risk factors. Sensitivity analyses were also conducted using Fine-Gray subdistribution hazard model regression, with death as a competing event. Results: Among 764 patients with ITP with 3540.8 person-years of follow-up, the incidence was 5.7 (95% CI, 4.9-6.5) per 100 person-years for arterial thrombosis and 2.1 (95% CI, 2.1 1.6-2.6) for venous thrombosis. The median age at thrombosis onset and the interval from ITP diagnosis to the index thrombotic event were 67.5 years and 2.4 years for arterial thrombosis and 62.0 years and 1.2 years for venous thrombosis, respectively. Recent 3-month exposure to all 3 ITP-targeted therapies increased the risk of both arterial and venous thrombosis. Conclusion: Advanced age, prior thromboembolism, comorbidities, recent exposure to ITP-targeted therapies, and cardiovascular risk factors were independent risk factors for thrombosis in ITP. Thromboembolism in ITP mostly occurred in the presence of multiple thrombotic risk factors. Continuous risk assessment and optimized management are essential throughout the clinical course of ITP.