Comparison of Martin and Friedewald equation for estimated LDL-C in adults

OBJECTIVE
In this study, we aimed to compare the directly measured low-density lipoprotein cholesterol (LDL-C), Friedewald, and a new Martin LDL-C formula in the Turkish adult population.

METHODS
A total of 1,558 patients between the ages of 18 and 65 years with a triglyceride level of <400 mg/dL were included in this study. Serum lipid profiles of all the patients were measured with Cobas 6000 c501 (Roche Diagnostic), and LDL-C concentrations were measured by a homogeneous direct method using reagents. [TC- (HDL-C+(TG/5)] and Martin [TC- (HDL-C+TG / new adjustable factor)] formulas were used to estimate LDL-C.

RESULTS
The average age of the patients was 52.7±12.3 years. Of the 1,558 patients, 56% were women and 44% were men. The d-LDL-C, F-LDL-C, and M-LDL-C concentrations in all the patients were 148.6±39.8 mg/dL, 123.9±38.7 mg/dL, and 133.4±35.9 mg/dL, respectively. The mean difference between F-LDL-C and M-LDL-C concentrations according to d-LDL-C was 24.6±10.7 and 15.10±10.3, respectively. For comparing the scatter blot plot [estimated LDL-C(x) and d-LDL-C(y)] were calculated by the equations y=1.1665x+0 for Friedewald and y=1.1667x+0 for Martin. When compared to the d-LDL-C concentration, both the Friedewald and Martin formulas showed a strong correlation (r=0.963, r=0.968, respectively). The new adjustable factor mean of the Martin formula was 6.1±0.9.

CONCLUSION
In our study, the Martin formula showed a relatively better separation. Although there was a strong correlation between the formulas and d-LDL-C, there was a negative bias for the two formulas. These formulas show a lower risk in the determination of the risk of coronary heart disease and in the planning of treatment strategies.