Do the Joint British Society (JBS2) guidelines on prevention of cardiovascular disease with respect to plasma glucose improve risk stratification in the general population? Prospective cohort study

Abstract

Aims: British guidelines on vascular disease prevention recommend adding a random (casual) blood glucose measurement to a lipid profile in those aged > or = 40 years. To assess this recommendation, we compared the predictive value of a risk model based on the Framingham risk score alone to one which additionally included information on fasting blood glucose, with respect to incident coronary heart disease (CHD) over 11 years.

Method: Men and women aged 40-63 years in Whitehall II were followed up for incident CHD: death/non-fatal myocardial infarction; angina confirmed by doctor diagnosis or electrocardiogram (ECG) and all first events. Fasting blood glucose was specified as a continuous variable or categorized by World Health Organization (WHO) 1999 glycaemic status (normal glucose tolerance, impaired fasting glucose or newly diagnosed diabetes).

Results: The hazard ratio for incident CHD was 1.10 (95%CI 1.09; 1.12) in men and 1.13 (1.10; 1.17) in women per percentage point increase in Framingham risk. The excess risk remained unchanged in models which added glycaemic status or continuous fasting glucose. The area under the receiver operating characteristic (ROC) curve for the Framingham score and incident coronary heart disease [0.70 (0.68; 0.73)] did not change when glycaemic status or fasting glucose was added to the prediction model. Reclassification with these modified models improved discrimination based on the Framingham score alone when glycaemic status was added, net reclassification improvement 2.4% (95% CI 0.2%; 4.6%), but not when fasting glucose was added.

Conclusion: Better detection of unrecognized diabetes is a valuable consequence of including a random blood glucose in a vascular risk profile. Our results suggest that this strategy is unlikely to improve risk stratification for CHD.