Discriminant ratio and biometrical equivalence of measured vs. calculated apolipoprotein B100 in patients with T2DM

Abstract

Doc number: 39

Abstract

Background: Apolipoprotein B₁₀₀ (ApoB₁₀₀ ) determination is superior to low-density lipoprotein cholesterol (LDL-C) to establish cardiovascular (CV) risk, and does not require prior fasting. ApoB₁₀₀ is rarely measured alongside standard lipids, which precludes comprehensive assessment of dyslipidemia.

Objectives: To evaluate two simple algorithms for apoB₁₀₀ as regards their performance, equivalence and discrimination with reference apoB₁₀₀ laboratory measurement.

Methods: Two apoB₁₀₀ -predicting equations were compared in 87 type 2 diabetes mellitus (T2DM) patients using the Discriminant ratio (DR). Equation 1 : apoB₁₀₀ = 0.65*non-high-density lipoprotein cholesterol + 6.3; and Equation 2 : apoB₁₀₀ = -33.12 + 0.675*LDL-C + 11.95*ln [triglycerides]. The underlying between-subject standard deviation (SD_U ) was defined as SD_U = [radical] (SD² _B - SD² _W /2); the within -subject variance (V_w ) was calculated for m (2) repeat tests as (V_w ) = Σ(x_j -x_i )² /(m-1)), the within-subject SD (SD_w ) being its square root; the DR being the ratio SD_U /SD_W .

Results: All SD_u , SD_w and DR's values were nearly similar, and the observed differences in discriminatory power between all three determinations, i.e. measured and calculated apoB₁₀₀ levels, did not reach statistical significance. Measured Pearson's product-moment correlation coefficients between all apoB₁₀₀ determinations were very high, respectively at 0.94 (measured vs. equation 1 ); 0.92 (measured vs. equation 2 ); and 0.97 (equation 1 vs. equation 2 ), each measurement reaching unity after adjustment for attenuation.

Conclusion: Both apoB₁₀₀ algorithms showed biometrical equivalence, and were as effective in estimating apoB₁₀₀ from routine lipids. Their use should contribute to better characterize residual cardiometabolic risk linked to the number of atherogenic particles, when direct apoB₁₀₀ determination is not available.