Comparison of the Framingham and United Kingdom Prospective Diabetes Study cardiovascular risk equations in Australian patients with type 2 diabetes from the Fremantle Diabetes Study

Authors: Wendy A Davis, Stephen Colagiuri and Timothy M E Davis

Med J Aust 2009; 191 (1): 47-48. || doi: 10.5694/j.1326-5377.2009.tb02684.x
Published online: 6 July 2009

In reply: We thank McCallum and colleagues for their comments. In relation to their specific points:

The Fremantle Diabetes Study (FDS) cohort is representative and drawn from a typical Australian urban centre.1 The 488 cardiovascular disease-free FDS participants with type 2 diabetes who were aged 25–65 years at both diagnosis and study entry had 22 coronary heart disease (CHD) events compared with 72 predicted, with a similar area under the receiver operating characteristic curve (AUC) to that for all 791 patients who were included in the analysis2 (0.66 v 0.68). Calibration indicated significant discrepancies between predicted and actual outcomes (P ≤ 0.02), and positive predictive values were low (≤ 3.5%). Therefore, restricting our patient sample to a “UKPDS” cohort did not alter our conclusions.
We agree that the low observed CHD event rate in the FDS compared with that predicted by the UKPDS risk engine undermines its validity in Australians with type 2 diabetes. There was a similarly low CHD event rate in the FIELD study, which included many Australasians.3 Contemporary diabetes care clearly differs from that during the Framingham Study and UKPDS.
Although the study cited by McCallum and colleagues, in a UK general practice population, is not strictly comparable to our study, it also found that the UKPDS cardiovascular disease risk engine performed only moderately (AUC, 0.72).4

1. School of Medicine and Pharmacology, University of Western Australia, and Fremantle Hospital, Fremantle, WA.
2. Boden Institute of Obesity, Nutrition and Exercise, University of Sydney, Sydney, NSW.

Correspondence: wdavis@cyllene.uwa.edu.au

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