CONSISTENCY OF FRIEDEWALD, MARTIN/HOPKINS AND SAMSON FORMULAS FOR LDL-C CALCULATION IN HIGH AND VERY HIGH CARDIOVASCULAR RISK PATIENTS

Abstract

Background and Aims : Friedewald formula is the most common used equation to calculate LDL-C levels. However, its accuracy has been questioned recently. We aimed to investigate the consistency of Friedewald (F), Martin/Hopkins (M) and Samson (S) formulas for calculated LDL-C levels, and the effect on target goal attainment for different LDL-C targets. Methods: The lipid parameters of EPHESUS study (multicenter, observational study conducted on high and very high CVD risk patients) participants were used to calculate LDL-C values according to three (F,M,S) formulas. Correlation was assessed by Pearson’s correlation coefficient among these formulas. The patients grouped according to triglyceride (TG) levels of <150 mg/dl, 150-250 mg/dl, and 250-400 mg/dl. Goal attainment rates at different LDL-C targets (<100 mg/dl, <70 mg/dl, and <55 mg/dl) were than compared. Results: Of the 1810 patients, correlation coefficients among formulas were 0.998, 0.996, and 0.991 for F&S, M&S, and F&M respectively (p<0.001). When patients were grouped according to TG levels 884 (48.9%) had <150 mg/dl, 663 (36.7%) had 150-250 mg/dl, and 261 (14.4%) had 250-400 mg/dl. A comparison of those patients according to different LDL-C target attainment rates (<100 mg/dl, <70 mg/dl, and <55 mg/dl) were shown on Figure. Conclusions: Although there was a good correlation among all formulas Friedewald formula tended to underestimate LDL-C values in patients with high triglyceride levels. Furthermore, the risk underestimation was highest for lower LDL-C levels. Hence it might be reasonable to use new formulas for LDL-C calculation in high and very high cardiovascular risk patients especially if their LDL-C values were close to targets.