A method for measuring glycerol-blanked triglyceride concentrations by using gas chromatography-isotope dilution mass spectrometry

Optimal Cut-off Points of Nonfasting and Fasting Triglycerides for Prediction of Ischemic Heart Disease in Japanese General Population: The Circulatory Risk in Communities Study (CIRCS)

AIMS

We investigated the optimal cut-off points of nonfasting and fasting triglycerides in Japanese individuals with lower average triglyceride levels than westerners.

METHODS

Residents aged 40-69 years without a history of ischemic heart disease or stroke were enrolled between 1980 and 1994 and followed. Serum triglyceride concentrations were measured from 10851 nonfasting (＜8 h after meal) and 4057 fasting (≥ 8 h) samples. As a prerequisite, we confirmed the shape of a receiver operating characteristic (ROC) curves, the area under ROC curves (AUC), and the integrated time-dependent AUC. We identified optimal cut-off points for incident ischemic heart disease based on C-statistic, Youden index, and Harrell's concordance statistic. We used dichotomized concentrations of triglycerides via the univariate logistic regression and Cox proportional hazards regression models. We also calculated multivariable hazard ratios and population attributable fractions to evaluate the optimal cut-off points.

RESULTS

Nonfasting and fasting optimal cut-off points were 145 mg/dL and 110 mg/dL, with C-statistic of 0.594 and 0.626, Youden index of 0.187 and 0.252, and Harrell's concordance statistic of 0.590 and 0.630, respectively. The corresponding multivariable hazard ratios of ischemic heart disease were 1.43 (95%CI 1.09-1.88) and 1.69 (1.03-2.77), and the corresponding population attributable fractions were 16.1% (95%CI 3.3-27.2%) and 24.6 (-0.3-43.3).

CONCLUSION

The optimal cut-off points of nonfasting and fasting triglycerides in the Japanese general population were 145 mg/dL and 110 mg/dL, respectively, lower than the current cut-off points recommended in the US and Europe.

LDL-cholesterol and PCSK9 in patients with familial hypercholesterolemia: influence of PCSK9 variants under lipid-lowering therapy

Background

Familial hypercholesterolemia (FH), an autosomal dominant genetic disease with the elevated levels of low‐density lipoprotein (LDL) cholesterol (LDL‐C), increases the risk of coronary artery disease (CAD). The proprotein convertase subtilisin/kexin type 9 (PCSK9) gene is associated with FH. There is a positive relationship between circulating LDL‐C and PCSK9 levels, a potential CAD condition, without lipid‐lowering therapy (LLT); however, we do not know whether their correlation exists in FH patients under LLT.

Methods

This study compared the correlation of PCSK9 variants among patients with FH under LLT (n = 70; mean age, 53 years; male, 63%). LDLR, PCSK9 and APOB variants were analyzed using next‐generation sequencing.

Results

The LDL‐C and PCSK9 levels in patients with gain‐of‐function (GOF) variants of PCSK9 (n = 7) were mostly similar to those in patients with LDLR variants (n = 17) or variant‐negative patients (n = 46). A significant positive correlation was observed between LDL‐C and PCSK9 levels in patients with GOF variants of PCSK9 (r = 0.79, p = 0.04), but not in patients with LDLR variants or variant‐negative patients.

Conclusion

The LDL‐C‐PCSK9 correlation is suggested to be retained in FH patients with GOF variants of PCSK9 even under LLT, and these variants can be used as molecular markers for additional treatment with statins in FH patients.