Short-term biological variation study of plasma hemophilia and thrombophilia parameters in a population of apparently healthy Caucasian adults.

OBJECTIVES: Biological variation (BV) data obtained in a standardized way is valuable to assess the analytical requirements and the utility of a reference interval. Our study aimed to determine the short-term BV of thrombophilia (protein S, protein C, activated protein C resistance (APCR) and factor VIII) and hemophilia (factors VIII, IX and XI) parameters in plasma. Coagulation factors V and XII were also evaluated. Based on the obtained data, we assessed analytical performance specifications for the parameters. Finally, we intended to provide a robust tool for comparison of serial measurements of factors V, VIII, IX and XI. METHODS: A blood draw was performed weekly in 19 apparently healthy Caucasian adults for five weeks at Saint-Luc University Hospital (Brussels, Belgium). Parameters were measured in duplicate. BV components were calculated with a nested analysis of variance after exclusion of outliers. RESULTS: The analytical coefficient of variation (CV) varied from 1.5 to 4.6%, the within-subject CV from 1.6 to 8.9% and the between-subject CV from 3.8 to 24.1%. All parameters showed high individuality. For most parameters, the analytical goal was met with our assays. Reference change values (RCV) of -16.7% to +20.0%, -20.7% to +26.0%, -15.3% to +18.1% and -13.1% to +15.1% were obtained for factors V, VIII, IX and XI respectively. CONCLUSIONS: All studied parameters were highly individualized. The assessment of BV data can guide setting analytical goal specifications. Comparison of serial measurements in the follow-up of patients suffering from hepatic failure or mild hemophilia is facilitated by evaluation of the RCV.

Biological variation data and analytical specification goal estimates of the thrombin generation assay with and without thrombomodulin in healthy individuals.

BACKGROUND: Evaluation of an individual's thrombin-generating capacity enables a global assessment of the coagulation cascade and is therefore thought to better reflect the clotting function of blood. However, the lack of standardization still hampers the use in routine clinical practice. METHODS: Nineteen healthy subjects were sampled once a week for 5 consecutive weeks. Thrombin generation assay (TGA) was performed in duplicate by calibrated automated thrombogram (CAT) on platelet poor plasma with and without thrombomodulin. After exclusion of outliers, a nested analysis of variance (ANOVA) was performed to evaluate the biological variability (BV) results. Analytical variation (CVA ), within-individual variation (CVI ), between-individual variation (CVG ), index of individuality (II), and reference change value (RCV) were calculated. RESULTS: All parameters taken together, the CVA, CVI , and CVG without TM, ranged from 2.8% to 6.5%, from 4.1% to 13.3% and from 10.4% to 28.4%, respectively. For TG with TM, CVI and CVG were higher and ranged from 5.0% to 18.1% and from 14.9% to 35.3%, respectively. For endogenous thrombin potential (ETP), a CVI of 4.1% and CVG of 10.4% were obtained without addition of thrombomodulin (TM). With addition of TM, both CVI and CVG were higher: 14.0% and 34.8%, respectively. The II was low and the RCV ranged from 17.2% to 50.4%. CONCLUSION: CAT parameters are highly individualized and population-based reference values could be called into question. The assessment of BV and RCV for thrombin generation assays could optimize interpretation of serial patient results and guide setting of analytical specification goals.

Time course of release of inflammatory markers after coronary stenting: comparison between bare metal stent and sirolimus-eluting stent.

BACKGROUND: High levels of release of inflammatory markers after coronary angioplasty are predictors of late restenosis. Sirolimus-eluting stent reduces the risk of restenosis. AIM OF THE STUDY: To compare the release of inflammatory markers after coronary angioplasty with sirolimus-eluting stent and bare metal stent. METHODS: Sixteen patients with a proximal left anterior descending coronery artery stenosis were randomly assigned to receive either bare metal stent (n = 8) or sirolimus-eluting stent (n = 8). We measured simultaneously aortic and coronary sinus concentrations of the von Willebrand factor antigen, tumor necrosis factor-alpha and interleukin-6 before, immediately and after 2 h after stenting. High-sensitivity C-reactive protein and troponin-I circulating levels were measured before and 6 and 24 h after coronary angioplasty. RESULTS: Before stenting, all values were similar in both groups. The coronary sinus change of the von Willebrand factor antigen level between baseline and 2 h after stenting was + 20.1 +/- 26.9% in the bare metal stent group and -5.7 +/- 23.02% in the sirolimus-eluting stent group (P < 0.05). We observed a significant increase in the von Willebrand factor antigen (from 132.8+/-58.8 to 169 +/- 40.7%, P < 0.05) systemic concentrations 24 h after stenting in the bare metal stent group but not in the sirolimus-eluting stent group (from 140.6+/-84% to 136 +/- 39.5%), P = NS). CONCLUSION: The present study shows that a difference in the release of inflammatory markers can be detected after coronary stenting with bare metal stent or sirolimus-eluting stent. The lower release of the von Willebrand factor antigen in the coronary sinus 2 h after the procedure and the lower systemic concentrations of the von Willebrand factor antigen 24 h after stenting in the sirolimus-eluting stent group are likely to reflect a reduced production of the von Willebrand factor antigen at the site of the vascular injury.