Evaluating CMR

The UKPDS risk engine

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As previously stated, individuals with type 2 diabetes are at increased CHD risk compared to the general population (24-26). It has been suggested that diabetic individuals with no CHD history have a similar risk of developing an acute myocardial infarction (MI) as nondiabetic individuals who have had a previous MI (27). Unfortunately, CHD prediction models such as Framingham risk equations (3) were not specifically designed for type 2 diabetic patients. These algorithms tend to underestimate CHD risk in individuals with type 2 diabetes (28). Moreover, these models do not consider diabetes-specific risk factors such as glycemic control and duration of diabetes. Accordingly, the UKPDS (6, 29) developed an equation for estimating the risk of new CHD events in men and women with type 2 diabetes. Unlike previous risk equations, the UKPDS risk model is diabetes-specific and incorporates glycemia.

The UKPDS cohort was composed of 4,540 patients with newly diagnosed type 2 diabetes. The inclusion criteria also encompassed fasting plasma glucose greater than 6 mmol/l and no previous history of MI, angina, or heart failure. The patients were recruited between 1977 and 1991 and underwent a follow-up of 10.7 years (median). In the model, CHD was defined as the incidence of fatal or non-fatal MI or sudden death. Baseline risk factors were age at diagnosis of diabetes, sex, ethnic group (Afro-Caribbean, Caucasian, or Asian-Indian), smoking status, HBA1c, systolic blood pressure, total cholesterol/HDL cholesterol ratio, and time since diagnosis of diabetes. For some variables, such as HBA1c, systolic blood pressure, and cholesterol/HDL cholesterol levels, year 1 and 2 measurements were averaged to improve model stability.

Reference

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3. Wilson PW, D'Agostino RB, Levy D, et al. Prediction of coronary heart disease using risk factor categories. Circulation 1998; 97: 1837-47.

6. Stevens RJ, Kothari V, Adler AI, et al. The UKPDS risk engine: a model for the risk of coronary heart disease in Type II diabetes (UKPDS 56). Clin Sci (Lond) 2001; 101: 671-9.

24. Barrett-Connor EL, Cohn BA, Wingard DL, et al. Why is diabetes mellitus a stronger risk factor for fatal ischemic heart disease in women than in men? The Rancho Bernardo Study. JAMA 1991; 265: 627-31.

25. Koskinen P, Manttari M, Manninen V, et al. Coronary heart disease incidence in NIDDM patients in the Helsinki Heart Study. Diabetes Care 1992; 15: 820-5.

26. Manson JE, Colditz GA, Stampfer MJ, et al. A prospective study of maturity-onset diabetes mellitus and risk of coronary heart disease and stroke in women. Arch Intern Med 1991; 151: 1141-7.

27. Haffner SM, Lehto S, Ronnemaa T, et al. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med 1998; 339: 229-34.

28. McEwan P, Williams JE, Griffiths JD, et al. Evaluating the performance of the Framingham risk equations in a population with diabetes. Diabet Med 2004; 21: 318-23.

29. The UK Prospective Diabetes Study. http://www.dtu.ox.ac.uk/index.php?maindoc=/ukpds/, last accessed in August 2007.

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