Platelet aggregation measured by impedance aggregometry is highly dependent on platelet count. We previously developed a tool to interpret impedance aggregometry based on the strong linear correlation between platelet counts and platelet aggregation at reduced platelet counts. The present study aimed to optimize the tool by expanding the model to include normal platelet counts. We combined data from three previous studies on 266 healthy individuals measuring impedance aggregometry with four agonists (collagen, adenosine diphosphate, thrombin receptor activating peptide-6, and ristocetin). Reduced platelet counts were established in vitro. The investigated platelet counts ranged from 26-425x109/L. A positive linear correlation was found between platelet counts and platelet aggregation across normal and reduced platelet counts (all p-values <0.001). We established 95% prediction intervals for healthy platelet aggregation in relation to platelet count. The new expanded model serves as an optimized tool for evaluation of platelet aggregation at normal and reduced platelet counts.
Keywords: Impedance aggregometry; platelet aggregation; platelet count; platelet function tests; thrombocytopenia.