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Biological variation of thromboelastrography variables in 10 clinically healthy horses
Author(s) -
Scruggs Jennifer L.,
Flatland Bente,
McCormick Karen A.,
Reed Ann
Publication year - 2015
Publication title -
journal of veterinary emergency and critical care
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.886
H-Index - 47
eISSN - 1476-4431
pISSN - 1479-3261
DOI - 10.1111/vec.12410
Subject(s) - medicine , coefficient of variation , horse , thromboelastography , veterinary medicine , population , prospective cohort study , zoology , nuclear medicine , statistics , mathematics , surgery , coagulation , biology , paleontology , environmental health
Objective To assess the utility of population‐based reference intervals (PRIs) for interpreting thromboelastography (TEG) variables in horses using biological variation data. Design Prospective cohort biologic variation study conducted over a 5‐week period. Setting Veterinary teaching hospital and research facility. Animals Ten clinically healthy horses randomly selected from a veterinary school research and teaching herd. Interventions Horse health was determined using physical examination, CBC, and biochemical and coagulation profiles prior to the start of the study. Subsequently, once weekly blood sampling for TEG testing was performed for 5 weeks. Measurements and Main Results The 4 TEG variables reaction time ( R ), clot formation time ( K ), angle, and maximum amplitude (MA) were measured, and coefficient of variation representing within‐ and between‐horse biological variation (CV i and CV g , respectively) and coefficient of variation representing analytical variation (CV a ) were calculated using a nested ANOVA after removing outlier data. The CV i , CV g , and CV a for R were 26.8%, 5.2%, and 5.9%; for K were 31.0%, 0.0%, and 5.9%; for angle were 9.4%, 6.2%, and 21.7%; and for MA were 3.4%, 4.1%, and 4.4%, respectively. Index of individuality (IOI) was then calculated for each variable using the formula{ ( CV i 2 + CV a 2 / CV g 2 ) } 1 / 2 . IOI for R was 5.3, for angle was 3.8, and for MA was 1.4; IOI was not assessed for K. Conclusions PRIs are appropriate for TEG variables, R , angle, and MA when interpreting results from individual horses based on calculated IOI values equal to or greater than 1.4. PRIs are likely appropriate when interpreting K , but IOI could not be calculated for this variable.