A practical technique for clinicians to approximate platelet function after fifteen-minutes using thromboelastography

BackgroundPoint-of-care platelet function tests are used by anaesthetists and surgeons to create risk management plans for patients who have recently taken antiplatelet medication. Thromboelastography (TEG), one method of determining platelet function, sometimes takes >60 minutes to produce results. Previous studies have shown a novel parameter, area under the curve at 15 minutes (AUC15), correlates with clinical outcomes but used privately-owned, custom-made software to calculate AUC15. This study aimed to create a formula that clinicians can use to approximate AUC15 which correlates to the most widely used measure of platelet function, percentage of platelet aggregation. MethodsPlatelet function after 15 minutes can be approximated by the equation: AUC15 = 225(tan({theta})) where {theta} = (MAADP/MAThrombin). A retrospective database review was performed on eligible platelet function tests that assessed ADP receptor inhibition on a TEG 6s Hemostasis Analyzer (Haemonetics(R)) across 15 months. Results were analysed using a bivariate scatter plot with linear regression line and a two-tailed Pearson correlation coefficient was calculated. ResultsForty-seven tests were retrieved, of which, forty-five were eligible for analysis. Pearson two-tailed correlation coefficient showed that AUC15 correlated significantly with percentage of platelet aggregation (R = 0.748, 95% CI [0.582, 0.854], p < 0.001). ConclusionThis study creates the first practical method for clinicians to approximate platelet function on TEG analysers after 15 minutes, instead of >60 minutes, using routinely generated outputs and a calculator. Clinicians who use this method will afford themselves more time to create risk management plans for patients which may improve patient outcomes.