Clinical ResearchA comparison of the PROCAM and Framingham point-scoring systems for estimation of individual risk of coronary heart disease in the Second Northwick Park Heart Study
Introduction
Many individual characteristics contribute to the risk of clinical coronary heart disease (CHD) including gender, age, blood lipid concentrations, blood pressure, glucose tolerance, adiposity, and cigarette smoking. The complexity of the inter-relations between these risk factors makes assessment of individual ‘global’ risk difficult to evaluate in routine clinical practice, and statistical approaches have been developed, based on survival regression methods (e.g. Cox proportional hazards regression) or logistic regression. To simplify this approach for everyday use, point-scoring systems have been developed that permit the impact of several risk factors to be considered simultaneously [1], [2]. The population distribution of each risk factor is divided into several categories (e.g. cigarette smoker: yes/no; high-density lipoprotein cholesterol (HDLc): <35, 35–54, 55+ mg/dL), and each category is given a risk score. These scores are totalled and the result converted into 10-year risk of a coronary event from tables.
Point-scoring schemes have been developed from the Framingham study in the USA [1] and the PROCAM study in Germany [2]. The PROCAM system includes age, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDLc), triglyceride, smoking, diabetes, family history of CHD, and systolic blood pressure as risk factors. The Framingham system does not include information on family history, diabetes, triglyceride, or LDLc, but does include total cholesterol and interactions of age with smoking and cholesterol. Both systems use acute CHD events as the end point. Not surprisingly, the Framingham system was not as accurate as the PROCAM system when applied to the PROCAM data set, and the proposal has been made that valid comparison of performance requires their application to a third and independent data set [2]. The Second Northwick Park Heart Study (NPHS-II), a prospective cardiovascular study of healthy middle-aged men, has provided the opportunity both for development of a point-scoring system using conventional and novel coronary risk factors [3], [4], [5], and comparison with Framingham and PROCAM in a British setting.
Section snippets
Subjects
Full details of the recruitment methods, participant characteristics, and baseline measurements have been published previously [3], [4], [5]. Serum HDLc was measured using polyethylene glycol 8000 and enzymatic colorimetry on the sample of plasma taken at year 5 [5] and values used to estimate LDLc for each subject using the Friedewald equation as described [5]. Briefly, NPHS-II is a prospective study of 3052 healthy middle-aged Caucasian men (50–64 years) recruited from nine United Kingdom
Application of PROCAM and Framingham scores to NPHS-II
The PROCAM and Framingham scoring systems were applied to the 2732 NPHS-II men with complete data. Serum HDLc and LDLc were not measured at baseline in NPHS-II and so levels for these variables were set to the average observed in a subset of over 2000 NPHS-II men after 5 years of follow-up (LDLc 4.0 mmol/L and HDLc 0.8 mmol/L). The ability of the scores to separate men with and without disease was assessed using ROC curve analysis (Fig. 1). The ROC area using PROCAM was 0.63 (95% CI, 0.59–0.67).
PROCAM and Framingham comparison
Assessment of CHD risk is commonly used to identify patients who may benefit from primary prevention, and these assessments have frequently been based on equations derived from the Framingham study. In the present study, the risk scoring systems developed from both Framingham and PROCAM data have been applied to a UK-based sample of middle-aged men. Since this sample was comprised of European men, it might be expected that the PROCAM system (derived for subjects in Germany) would predict their
Acknowledgements
The following general practices collaborated in the study: The Surgery, Aston Clinton, Upper Gordon Road, Camberley; The Health Centre, Carnoustie; Whittington Moor Surgery, Chesterfield; The Market Place Surgery, Halesworth; The Health Centre, Harefield; Potterells Medical Centre, North Mymms; Rosemary Medical Centre, Parkstone, Poole; The Health Centre, St. Andrews. NPHS-II was supported by the UK Medical Research Council, the US National Institutes of Health (grant NHLBI 33014) and Du Pont
References (30)
- et al.
Lipoprotein(a) as a predictor for myocardial infarction in middle-aged men
Am J Med
(2001) - et al.
Soluble thrombomodulin as a predictor of incident coronary heart disease and symptomless carotid artery atherosclerosis in the Atherosclerosis Risk in Communities (ARIC) study: a case-control study
Lancet
(1999) - Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection,...
- et al.
Simple scoring scheme for calculating the risk of acute coronary events based on the 10-year follow-up of the prospective cardiovascular Munster (PROCAM) study
Circulation
(2002) - et al.
Comparison of novel haemostatic factors and conventional risk factors for prediction of coronary heart disease
Circulation
(2000) - et al.
Increased activation of the haemostatic system in men at high risk for fatal coronary heart disease
Thromb Haemost
(1996) - et al.
Non-fasting apolipoprotein B and triglyceride levels as a useful predictor of coronary heart disease risk in middle-aged UK men
Arterioscler Thromb Vasc Biol
(2002 (November 1)) - World Health Organization Regional Office for Europe. Myocardial Infarction Community Registers. Copenhagen, Denmark:...
- et al.
The Minnesota Code Manual of Electrocardiographic Findings
(1982) - et al.
Comparing the areas under two or more correlated receiver operating curves: a non-parametric approach
Biometrics
(1988)
Correction of logistic regression relative risk estimates and confidence intervals for random within-person measurement error
Am J Epidem
Are the Framingham and PROCAM coronary heart disease risk functions applicable to different European populations. The prime study
Eur Heart J
Cardiovascular risk and diabetes: are the methods of risk prediction satisfactory?
Eur J Cardiovasc Prev Rehab
Framingham risk function overestimates risk of coronary heart disease in men and women from Germany: results from the MONICA Ausburg and the PROCAM cohorts
Eur Heart J
Comparison of the Framingham risk function-based coronary chart with risk function from an Italian poulation study
Eur Heart J
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