Comparison between Friedewald's and Sampson's formulas in the estimation of high levels of measured LDL-cholesterol in youth with obesity

Background and aim: To assess the performance of Friedewald's and Sampson's formulas in relation to high or borderline-high levels of measured LDL-Cholesterol (LDL-C) in youths with overweight/obesity (OW/OB). Methods and results: A cross-sectional study was performed in 1694 youths (age 5–17 years) with OW/OB observed in Italian centers of Messina (group 1) and Naples (group 2). LDL-C levels were both measured and calculated using Friedewald's (LDL-CF) and Sampson's (LDL-CS) formulas. The two groups were similar for sex, age, BMI, BMI Z-score, and measured LDL-C. Levels of LDL-CF and LDL-CS were higher in group 1 than group 2. In the overall sample, 9.9 % youths had measured LDL-C ≥130 mg/dL and 27.8 % ≥ 110 mg/dL, without differences between centers. The two formulas showed comparable high sensitivity and specificity in relation to levels of measured LDL-C ≥130 mg/dL or ≥110 mg/dL. However, LDL-CF showed a higher positive predictive value than LDL-CS. Conclusions: Both formulas estimate with high accuracy measured LDL-C levels in youths with OW/OB. Therefore, calculated LDL-C can be a useful tool for universal screening when direct LDL-C measurement is not available. The Friedewald's formula is more feasible in clinical practice for simplicity of calculation.