Reactive thrombocytosis and the risk of thrombo-embolism in a general hospital population

F Lambers, J.W.J. van Esser, A.A.M. Ermens, P.A.W. te Boekhorst, C. van Guldener

Woensdag 20 april 2016

15:50 - 16:00u in Zaal 0.4

Categorie├źn: Parallelsessie

Parallel sessie: Parallelsessie 3: Case reports/research

Background: Reactive thrombocytosis is a platelet count of >450 x 109/L in the absence of a myeloproliferative disorder. It is generally considered not to be associated with an increased risk of a thrombosis, but recent studies suggest that this might not be true. In this study, we examined the relationship between reactive thrombocytosis and thrombosis in a large hospital population.

Methods: All adult patients in whom a thrombocytosis was detected in 2014 at the Amphia hospital were screened (n=3828). All patients with thrombocytes of >800 x 109/L (n=377) were included. From the remaining patients, two groups of 377 patients were randomly selected with thrombocytes of 600-799 x 109/L and 450-599 x 109/L (total n=1131). The primary endpoint was the development of arterial or venous thrombosis or death during three months of follow-up. Cox proportional hazards regression methods were used for statistical analysis.

Results: 1042 patients (92%) had a reactive thrombocytosis. In these patients, the primary endpoint was reached in 8.0%, 8.3% and 6.3% in the groups with thrombocytes >800 x 109/L, 600-799 x 109/L and 450-599 x 109/L, respectively (NS). The only variable that was independently related to the primary endpoint was malignancy (RR 3.67; 95% CI: 2.13-6.30; P<0.0005). When the development of thrombosis only was taken as endpoint, only malignancy showed a tendency towards significance (RR 2.44; P=0.064).

Conclusion: In this study, a higher thrombocyte count in reactive thrombosis was not associated with an increased risk of thrombosis.