Editor,—Predicting the risk of coronary heart disease will always be prone to error. Haq et al compared four different risk functions1: the Framingham (USA),2 PROCAM (prospective cardiovascular Münster, German),3 Dundee (UK),4 and British regional heart study (UK) risk5 functions. These functions were applied to 206 male patients attending the Sheffield hypertension clinic. Haq et al used Bland–Altman difference plots to compare methods. Although they claim good agreement among the Framingham, PROCAM, and Dundee functions, close inspection shows that the difference in risk in the Framingham—PROCAM plot greatly increases above a mean coronary heart disease risk of 4% (fig 1B), and points in the Framingham—Dundee plot diverge …