Martin's, Friedewald's and Cordova's formulas compared to LDL-C directly measured in Southern Brazil

ABSTRACT Introduction: Recently, fasting flexibility for laboratory determination of lipid profile has been recommended. When triglycerides (TG) are above 400 mg/dl, the formula proposed by Martin et al. should be used to estimate the low-density lipoprotein cholesterol (LDL-C). However, this formula has not been evaluated in our population. Objectives: We evaluated the performance of Martin’s equation for LDL-C estimation compared to Cordova & Cordova and Friedewald formulas in a population of Southern Brazil. Methods: Sampling consisted of 10,664 Brazilian individuals (5,847 women) aged 1 to 93 years, with TG, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and LDL-C directly measured. Results: Martin’s formula presented significantly higher LDL-C values in patients with TG < 300 mg/dl, underestimating values when TG > 400 mg/dl, even with negative values; and LDL-C values was also overestimated in all TC ranges, with greater standard deviation. It also presented a higher mean error in the stratified intervals, and a lower correlation coefficient. Conclusion: Martin’s equation is not accurate for estimating LDL-C in our sample, unless TG is between 300 and 400 mg/dl. We recommend using the Cordova & Cordova formula as an alternative to determine LDL-C when its direct measurement is not available, and not applying the Martin’s Formula indiscriminately to other populations before it is properly evaluated and compared with other available equations.