Smoking and a history of atrial fibrillation may be possible risk factors for thrombotic events in a population of Japanese patients with immune thrombocytopenia (ITP), according to study results published in the Annals of Hematology.

This retrospective study involved 303 patients who had been newly diagnosed with ITP, and they were followed for outcomes of thrombosis, bleeding events, and survival. The study was conducted at Jichi Medical University in Shimotsuke in Japan.

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Patients had a median age of 63 years at time of diagnosis. At median follow-up of 3.6 years (range, 0-16.7), a total of 16 thrombotic events were reported. Thrombosis occurred with a 5-year cumulative incidence of 5.3% and a 10-year cumulative incidence of 10%.

In univariate analysis, features associated with thrombosis included male gender and patient histories of atrial fibrillation, hypertension, smoking, and prior thrombosis. In subsets of patients tested for several autoantibodies, including lupus anticoagulant, positivity was not associated with thrombotic events.

In multivariate analysis, features independently associated with thrombosis included history of atrial fibrillation (hazard ratio [HR], 8.79; 95% CI, 1.37-56.5; P =.02) and smoking (HR, 4.39; 95% CI, 1.28-15.1; P =.02). Smoking and atrial fibrillation history were also independent risk factors for arterial thrombosis.

Of 3 investigated treatments for ITP, none showed an increased association with thrombotic events. In terms of risk of thrombotic events, glucocorticoids had an HR of 1.53 (P =.42), thrombopoietin receptor agonist therapy had an HR of 1.07 (P =.95), and splenectomy had an HR of less than 0.01 (P =.99).

The 5-year rate of overall survival was 92% in this study population. Bleeding occurred with a 5-year cumulative incidence of 5.6%.

The researchers explained that this study did not show the same associations with thrombosis risk that have been shown in other prior studies. “We evaluated the risk for thrombosis in Japanese ITP patients and showed that the risk factors for thrombosis may be different in Japanese patients compared with other populations,” the researchers concluded.

Reference

1.     Ito S, Fujiwara SI, Ikeda T, et al. Evaluation of thrombotic events in patients with immune thrombocytopenia [published online December 18, 2019]. Ann Hematol. doi:10.1007/s00277-019-03886-6