Summary
The variability of haemostatic factor measurements in patients presenting with angina
pectoris is investigated. In all, 219 middle aged patients (almost all men) provided
repeat measurements 2.5 years apart on a battery of haemostatic and haematological
tests and other cardiovascular risk factors. Correlations between repeat measurements
were lower than might be expected in a healthy population, reflecting a relatively
large degree of variability within individuals over time. The highest correlations
observed for haemostatic factors were for von Willebrand factor related antigen (r = 0.48) and fibrinogen (r = 0.45). The correlations were generally lower amongst patients who had undergone
coronary surgery or angioplasty between the two measurements. We conclude that the
underlying relationship of fibrinogen to coronary risk must be much greater than is
generally appreciated, since even single measurements are found to be important predictors
of risk, despite only moderate stability over time. The very low correlations for
β-thromboglobulin (r = 0.10) and platelet factor 4 (r = 0.03) which were observed in this study casts doubt on their potential usefulness
as predictors of long-term cardiovascular risk.
