Platelet function in adult ITP patients can be either increased or decreased, compared to healthy controls, and is associated with bleeding risk

Abstract

Objectives: To test whether, together with platelet count, platelet activity could be an important predictor of bleeding risk in immune thrombocytopenia (ITP) patients. Methods: Platelet activity was tested by flow cytometric measurement of agonist induced P-selectin expression and compared between 23 adult ITP patients and 22 healthy volunteers. Results: Platelet activity could be either increased or decreased in ITP patients, compared to healthy volunteers. In the lowest platelet count category, normal to low platelet activity was associated with the biggest increase in bleeding risk. Risk difference 80% (95% confidence interval: 45–115%) for <32 × 109 platelets/L. For higher platelet counts, there was no association of platelet activity with bleeding risk. Discussion: Increased platelet activity was associated with decreased bleeding risk, but only in patients with low platelet counts. Conclusion: Platelet activity can be a predictor of bleeding risk in ITP patients with low platelet counts.