Assessment of platelet activation indices using the ADVIA (TM) 120 amongst 'high-risk' patients with hypertension

Background. Platelet activation is involved in the pathogenesis of the thrombotic complications of hypertension. Novel surrogate markers of platelet activation (mean platelet volume (MPV), mean platelet component (MPC, measure of platelet density), platelet component distribution width (PCDW, a marker of platelet shape change) and the number of platelet clumps) have been related to cardiovascular risk. We hypothesized a stepwise increase in these platelet activation indices between healthy controls (HC, n = 60), 'high-risk' essential hypertensive subjects (HBP, n = 45) and treated, previously diagnosed patients with malignant phase hypertension (MHT, n = 45). Methods. In a cross-sectional study, we measured comparative platelet counts and indices of platelet activation (MPV, MPC, PCDW and the number of platelet clumps) using the Bayer ADVIA(TM) haematology system, in our three study groups. Results. There was a stepwise increase in MPV (P = 0.0002) and MPM (P = 0.03), and a stepwise decrease in the MPC (P = 0.03) and PCDW (P = 0.001) across the three study groups, despite similarities in platelet count. These differences were only significantly different (on post-hoc analysis) between the healthy controls and the MHT group. On multivariate analysis, there was a significant relationship (R-2 = 66.5%; P <0.0001) between the MPV and the PCDW (P <0.0001), systolic blood pressure (P = 0.008) and platelet count (P <0.0001). Conclusion. There is a stepwise increase in platelet activation indices, despite similar platelet counts, with increasing severity of hypertensive disease. This may contribute to the pathogenesis of thrombosis-related complications in hypertension.