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PAPERS: Kiran Nanchahal, John R Duncan, Paul N Durrington, and Rodney T Jackson Analysis of predicted coronary heart disease risk in England based on Framingham study risk appraisal models published in 1991 and 2000 BMJ 2002; 325: 194-195 [Full text]

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Choice of CHD risk equations

Richard Milne   (30 July 2002)

Choice of CHD risk equations 30 July 2002
Richard Milne, Associate Professor University of Auckland Send response to journal: Re: Choice of CHD risk equations	Sir The paper by Nanchahal and colleagues (BMJ, July 27) indicates that substantially lower numbers of men and women without overt cardiovascular disease would be eligible for drug treatment if the standard 1991 Framingham CHD risk equation that is used in the Joint British Cardiovascular Recommendations were to be replaced with the 2000 model. This would be an important finding for cardiovascular guideline developers and budget holders if the newer risk equation had substantially more discriminability (accuracy) than the old one. However, this seems unlikely because the new risk equation is based on a modest number of endpoints (224 for men and 108 for women) and the equation for men incorporates the same set of risk factors as the 1991 equation. What guideline developers need is a comparison of each risk equation with observed incident cardiovascular events, preferably over a range of thresholds (a receiver-operator characteristics analysis). Published ROC analyses show that Framingham risk equations have only modest discriminability against observed CHD events (Wilson et al. 1998; Grover et al. 2000). We have also shown that the 1991 and 2000 CHD risk equations have very similar discriminability for CHD events in a New Zealand cohort(unpublished data). Fortunately for guideline developers, the interesting findings reported in this paper do not provide a good reason to abandon the 1991 Framingham CHD risk equations in favour of the 2000 version. However, cardiovascular guidelines will need to be revised when better risk equations become available. Richard Milne Associate Professor Divisions of Pharmacology and Community Health University of Auckland New Zealand Grover SA, et al. (2000). Lipid screening to prevent coronary artery disease: a quantitative evaluation of evolving guidelines. Canadian Medical Association Journal 163(10): 1263-9 Wilson PW, et al. (1998). Prediction of coronary heart disease using risk factor categories. Circulation 97(18): 1837-47 The author has no competing interests