Should treatment recommendations for lipid lowering drugs be based on absolute coronary risk or risk reduction?

When individual variables were subjected to logistic regression, male sex, age, blood pressure, smoking status, and cholesterol concentrations were all significant predictors of heart disease but when corrected for the Framingham risk score no single factor remained predictive on its own. The figure shows the number of coronary events predicted by the Framingham model and the number observed during follow up. The agreement is good at a predicted event rate above 30% (1.5% per year), with no significant difference between the observed and expected event rates (P = 0.85). However, at lower event rates the predictive model significantly underestimates the number of observed events (P < 0.01). The wide confidence intervals indicate that there is significant overlap between risk scores in those participants who developed heart disease and those who did not. Comment These results confirm that the Framingham model reliably predicts the absolute risk of heart disease in white men and women in the United Kingdom when the annual risk is above 1.5% , but the model underestimates the risk when the absolute risk is lower. This is consistent with studies that have shown that the model is inaccurate when applied to low risk populations. 5 We might have achieved a closer fit with the model by measuring concentrations of high density lipoprotein cholesterol and using a 4 to 12 year follow up period similar to that from which the model was derived. Nevertheless, the recommended threshold for treatment with lipid lowering drugs is based on an annual risk of 3% per year, 1 so the Framingham model can be used in clinical practice in the UK population. We would like to thank Drs M Tunbridge and D Appleton for providing access to the data from the Whickham study and Professor Gilbert MacKenzie for helpful comments on the manuscript. Contributors: SR and RHN developed the computer database and used it to analyse the data, as suggested by MPJV. MPJV and JMF provided the data. PC provided advice on data analysis and presentation. The paper was written by all of the authors. RHN is guarantor for the study.ing lipid-lowering drug therapy for primary prevention of coronary disease: an updated Sheffield table. The development of ischemic heart disease in relation to autoimmune thyroid disease in a 20 year follow-up of an English community. An updated coronary risk profile: a statement for health professionals. Current guidelines for prescribing lipid lowering drugs are …