Comparison of estimated LDL cholesterol equations with direct measurement

Abstract

Abstract Aim LDL-cholesterol is one of the most important risk factors for coronary heart disease (CHD). These equations use total cholesterol, HDL and triglycerides measurements. Friedwald equation sometimes shows variatiοn in LDL calculation, mainly in patients with extreme values of triglycerides and LDL cholesterol. The aim of this study is to evaluate the accuracy of 12 well-known equations (Friedewald, Vujovic, Chen, Puavillai, Cordova, Anandaraja, Hattori, Ahmadi, Sampson, Planella, Ephraim, Martin). Methods A sample of 280 patients was studied, of which 33% had CHD history (table 1). The agreement of the equations with measured LDL was calculated both with goodness of fit test (r-Pearson) and test of discrimination (ROC curves). Results The Martin equation showed the best agreement (r=0.955,95% CI:(0.944,0.964)), with similar results given by the Sampson equation (r=0.954). The widely used Friedewald equation seems to fall short with r=0.939 as does the Planella equation (r=0.916), which is the only one that takes Apo-B values into account. Other simple linear equations did not differ greatly in accuracy from the Friedewald equation (table 2). Also in extreme triglycerides values (> 300mg/dl) the Sampson equation showed a better performance (r=0.935) than the Martin equation (r=0.928). Conclusions Equations such as those of Sampson and Martin take into account the interaction between triglycerides and non-HDL cholesterol and appear to be superior to simple linear ones (eg, Friedewald equation) in the accuracy of predicting LDL-cholesterol values even in individuals with elevated VLDL, IDL and non-HDL cholesterol. Further research is needed to verify our results.Descriptive characteristics of the studyCorrelations table