Variations in Ex-Vivo Assessments of Hemostasis.

Abstract

Previous studies have described differences in hemostasis between Caucasians and African-American subjects, suggesting that ethnicity may influence parameters used to monitor hemostasis. During the course of post-hoc analyses of data from an ex-vivo model to evaluate hemostasis in healthy, non-coagulopathic individuals, evidence of ethnic variability was noted. In this study, ex-vivo assessments of hemostasis were conducted using the thromboelastograph assay (TEG), and Hemodyne Hemostasis Analyzer (HHA). These instruments provide an assessment of platelet function and clot formation. All the subjects enrolled in this trial were healthy male volunteers between the ages of 18 and 45 years. Of the 48 subjects enrolled, 34 (71%) were Caucasians and 14 (29%) were African-Americans. Analyses were performed comparing blood loss volume (assessed by systematic recording of filter paper weights), duration of bleeding, TEG and HHA tracings between the two groups. There were no significant differences in blood loss volume and duration. However in the African-American subjects, TEG analyses demonstrated a significantly higher clot growth rate and maximum clot amplitude strength, while HHA analyses demonstrated a significantly higher platelet contractile force. These observations suggest that ethnic differences in coagulation parameters may exist that could influence techniques or instruments used to evaluate hemostasis. These observations require further investigation. In addition, these observation may provide a useful avenue for further investigation of the apparent enhanced coagulability in the African-American population.Ex-vivo Assessments of HemostasisAfrican-AmericanCaucasiann=14n=31Mean ± SDMean ± SDp-valueBlood loss volume (g)2.19 ± 1.162.58 ± 1.84NSBleeding duration (mins)21.07 ± 7.5220.0 ± 7.21NSTEG resultsCoagulation onset time (R, mins)4.93 ± 0.725.40 ± 0.89NSTime to 20 mm clot strength (K, mins)1.59 ± 0.251.95 ± 0.290.0004Clot growth rate (A, degrees)67.17 ± 3.7863.15 ± 3.690.0017Max. clot amp. Strength (MA, mm)61.07 ± 3.8957.63 ± 3.960.0096HHA resultsClot elastic modulus (CEM, Kdynes/cm2)20.01 ± 5.8015.87 ± 7.51NSPlatelet contractile force (PCF, Kdynes)5.50 ± 1.114.42 ± 1.440.0165NS, Not statistically significant