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ARIC hemostasis study--IV. Intraindividual variability and reliability of hemostatic factors. The Atherosclerosis
N D Nguyen1, H Ghaddar, V Stinson
1Division of Hematology, University of Texas Medical School, Houston 77030, USA.
Insights
This study assessed the reliability of hemostatic factors in blood samples. Beta-thromboglobulin and tissue-plasminogen activator showed high reliability, while others had intermediate to low reliability.
Area of Science:
- Epidemiology
- Hematology
- Biostatistics
Background:
- Previous research established short-term intraindividual variability for some coagulation factors.
- Understanding the variability of additional hemostatic factors is crucial for accurate clinical interpretation and research.
Purpose of the Study:
- To quantify the intraindividual variability of additional hemostatic factors.
- To estimate the reliability of measurements for these factors.
Main Methods:
- Blood samples were collected from 39 subjects at three 1-2 week intervals.
- Variances (within-person, method, between-person) were estimated.
- Reliability coefficient (R) was calculated as the proportion of between-person variance.
Main Results:
- High reliability (R > 0.80) was observed for beta-thromboglobulin and tissue-plasminogen activator.
- Intermediate reliability (R ≈ 0.72-0.73) was found for D-dimer and plasminogen activator inhibitor-1.
- Low reliability (R < 0.50) was noted for Protein S, platelet factor 4, and fibrinopeptide A, often due to method or within-person variability.
- Gender, age, and factor levels did not impact intraindividual variability.
Conclusions:
- Reliability varies significantly among hemostatic factors.
- Beta-thromboglobulin and tissue-plasminogen activator are reliable for short-term intraindividual assessment.
- Factors like Protein S and fibrinopeptide A require careful consideration due to measurement variability.
Abstract:
We have recently reported the short-term intraindividual variability of several coagulation factors and inhibitors included in the ARIC study (Chambless et al. Ann Epidemiol 1992; 2:723). In this paper, we reported the intraindividual variability results of additional hemostatic factors. Blood samples were collected for hemostatic assays three times at 1-2-week intervals from 39 subjects recruited from 4 ARIC field centers. The contributions of within-person, processing and assay (designated "method") and between-person variances to the total variance were estimated and from them the reliability coefficient, R, was computed as the proportion of total variance in the between-person component. The R value was high for beta-thromboglobulin and tissue-plasminogen activator: 0.83 and 0.81, respectively; and intermediate for D-dimer and plasminogen activator inhibitor-1: 0.73 and 0.72, respectively. Protein S (total and free) and platelet factor 4 had low repeatability (R < 0.50) derived mostly from "method" variability while low R value (0.03) for fibrinopeptide A was attributed to high "method" and "within-person" variability. Gender, age and the level of hemostatic factors did not influence the intraindividual variability.