Resonance-thrombography indices of the haemostatic process in relation to risk of incident coronary heart disease: 9 years follow-up in the Caerphilly Prospective Heart Disease Study.

Global assays, such as resonance-thrombography (RTG), which measure the interaction between platelets, coagulation and fibrinolysis have been used as summary measures of risk for over two decades but have not been evaluated in epidemiological studies. We examined whether RTG indices are risk indicators for incident coronary heart disease (CHD). RTG indices, related haematological variables and other risk factors were measured between 1984 and 1988 in a cohort of 2398 British men. Reaction time (r) and amplitude of fibrin leg (AF) were associated with lifestyle risk factors. During 9 years of follow-up, 282 (12%) men developed a major new CHD event, as classified by World Health Organization criteria. On adjustment for age, only r and AF measured at baseline were related to risk of incident CHD. On multivariate adjustment in a multiple logistic regression model that included age, diastolic blood pressure, body mass index, total and high-density lipoprotein cholesterol, lifestyle risk factors and use of prescribed medicine, these associations weakened but remained significant. Additional adjustment for fibrinogen, viscosity, white cell count and fibrin d-dimer either reduced these associations to non-significance (AF) or to borderline significance (r).

Is type A behavior really a trigger for coronary heart disease events?

OBJECTIVE: The purpose of this study was to compare chronic with acute mechanisms by which Type A might predict incident coronary heart disease (CHD). METHOD: The study included 2394 men aged 50 to 64 years who were assessed for CHD, Type A behavior, and CHD risk factors. Type A was assessed using the Jenkins Activity Survey (JAS), the Bortner scale, and the Framingham scale. Further examinations were completed at 5 and 9 years for incident CHD. RESULTS: After 9 years, there was no increased risk of CHD associated with any Type A score. Nevertheless, high Bortner scores were associated with increased risk of incident CHD at 5 years and high JAS and Bortner scores were associated with a decreased risk between 5 and 9 years. Further analysis of Type A scores on time to first coronary event found strong inverse associations for all type A scores (JAS = 205 -0.49 months to first event, 95% CI = -0.20, -0.78, p =.001) (Bortner = 176 -0.27 months; 95% CI = -0.10, -0.44; p =.002) (Framingham = 0.44 -0.0011 months; 95% CI = -0.0002, -0.0019; p =.01). CONCLUSIONS: The data show Type A is a strong predictor of when incident coronary heart disease (or coronary event) will occur rather than if it will occur. These findings suggest that Type A increases exposure to potential triggers, rather than materially affecting the process of atherosclerosis.

High density lipoprotein subfractions and the risk of coronary heart disease: 9-years follow-up in the Caerphilly Study.

Whether the protective effect of high density lipoprotein (HDL) on incident coronary heart disease (CHD) can be attributed to one or both HDL subfractions remains controversial. The associations of HDL(2) and HDL(3) cholesterol with the incidence of CHD in the 9-year follow-up of the Caerphilly study are described. A total of 2398 middle-aged British men were recruited from the general population between 1984 and 1988 and were followed, on average, for 9 years. Total and HDL(3) cholesterol were measured by a two-step precipitation technique on fresh, fasting samples from 2225 men. HDL(2) cholesterol was calculated by subtracting HDL(3) from total HDL cholesterol. Relative odds and 95% confidence intervals (CI) for incident CHD were obtained by use of a logistic regression model. During follow-up, 282 (12%) men developed a major new CHD event. Total HDL and HDL(3) cholesterol were significantly and inversely associated with the risk of incident CHD. When divided into fifths of the distributions of total HDL and HDL(3) cholesterol, multivariate-adjusted relative odds were 1.00, 0.95, 0.72, 0.85, 0.38 and 1.00, 1.05, 0.92, 0.67, 0.39, respectively graded from the least to the most quintile, with the lowest quintile group as referent. Tests for trend were significant (P for trend 0.003 and 0.001, respectively). In a multivariate model, the contribution of HDL(3) was significant (standardized relative odds, 0.76; 95% CI, 0.64-0.91), whereas HDL(2) was not significant. No linear combination of the two subfractions was a better predictor of CHD than total HDL cholesterol alone. HDL(3) cholesterol was an independent predictor of incident CHD and may be more closely related to the development of CHD than HDL(2) cholesterol. The prediction of the risk of CHD from total HDL cholesterol alone could not be improved upon by measurement of the two HDL subfractions. In our view, the only way to improve our understanding of this situation is to measure both subfractions independently of each other and not to calculate one by subtraction.