Sources of Variability in Coagulation Factor Assays

Summary

Estimates of the components of variation of a number of coagulation factor assays are presented and are compared with those for other haematological and biochemical variables. They have been derived from a study in which fourteen volunteers gave blood samples approximately bi-monthly for three years. The systematic between-batch variation w⁷as generally only a small component of the total variation. However, the proportion of the total variation due to differences between people ranged from about 15% in the case of two measures of antithrombin III to about 85% for cholesterol and haemoglobin. For factor VII activity and fibrinogen, the figure was just over 70%. These estimates of the components of variation are not generally available in the literature. In view of the increasing interest in the role of coagulation factors in the pathogenesis of arterial disease, estimates of this kind are needed both for the interpretation of observed relationships as well as for planning sample sizes for future studies.

Keywords

Coagulation factors - Components of variability

• References

• 1 Meade TW, Brozovic M, Chakrabarti RR, Haines AP, Imeson JD, Mellows S, Miller GJ, North W RS, Stirling Y, Thompson SG. Haemostatic function and ischaemic heart disease: principal results of the Northwick Park Heart Study. Lancet 1986; 2: 533-537
• 2 Wilhelmsen L, Svärdsudd K, Korsan-Bengtsen K, Larsson B, Welin L, Tibblin G. Fibrinogen as a risk factor for stroke and myocardial infarction. N Engl J Med 1984; 311: 501-505
• 3 Crandon AJ, Peel KR, Anderson JA, Thompson V, McNicol GP. Postoperative deep vein thrombosis: identifying high-risk patients. Br Med J 1980; 281: 343-344
• 4 Fearnley GR, Chakrabarti R. Fibrinolytic treatment of rheumatoid arthritis with phenformin plus ethyloestrenol. Lancet 1966; 2: 757-761
• 5 Denson K WE, Borrett R, Biggs R. The specific assay of prothrombin using the Taipan snake venom. Br J Haematol 1971; 21: 219-226
• 6 Brozovic M, Stirling Y, Harricks C, North W RS, Meade TW. Factor VII in an industrial population. Br J Haematol 1974; 28: 381-391
• 7 Denson K WE. The use of antibodies in the study of blood coagulation. Blackwell; Oxford: 1967
• 8 Denson K WE. The specific assay of Prower-Stuart factor and factor VII. Acta Haematol 1961; 25: 105-120
• 9 Laurell C-B. Electroimmunoassay. Scand J Clin Lab Invest 1972; 29 suppl (124) 21-37
• 10 Abildgaard U, Lie M, Odegard OR. Antithrombin (heparin cofactor) assay with new chromogenic substrates. Thrombos Res 1977; 11: 549-553
• 11 Fearnley GR, Chakrabarti R. Increase of blood fibrinolytic activity by testosterone. Lancet 1962; 2: 128-132
• 12 Siedel J, Schlumberger H, Klose S, Ziegenhorn J, Wahlefeld AW. Improved reagent for the enzymatic determination of serum cholesterol. J Clin Chem Clin Biochem 1981; 19: 838-839
• 13 Bucolo G, David H. Quantitative determination of serum triglycerides by the use of enzymes. Clin Chem 1973; 19: 476-482
• 14 Snedecor GW, Cochran WG. Statistical methods. pp 171-172 and 238-54 7th edition. Iowa State University Press; 1980
• 15 Schweder T. A simple test for a set of sums of squares. Appl Statist 1981; 30: 16-21
• 16 Armitage P. Statistical methods in medical research. pp 201-202 Blackwell; Oxford: 1971
• 17 Chatfield C. The analysis of time series: theory and practice. pp 23-24 Chapman and Hall; London: 1975
• 18 North W RS, Stirling Y, Meade TW. Variation between batches in clotting factor assays. Thromb Haemostas 1982; 48: 274-278
• 19 Whitehead TP. Quality control in clinical chemistry. p 38 Wiley; New York: 1977
• 20 Altman DG. Statistics and ethics in medical research: III How large a sample?. Br Med J 1980; 281: 1336-1338