Adjustment Formula for Harmonizing Triglyceride Values in the Korea National Health and Nutrition Examination Survey, 2005-2022.

Background: Korea National Health and Nutrition Examination Survey (KNHANES) triglyceride testing changed from the glycerol blanking method (2005-2021) to the glycerol nonblanking method (2022). We converted triglyceride data from 2005-2021 to that obtained since 2022 with different analytical methods.

Methods: To develop a conversion equation, 98 fresh serum specimen pairs were compared using Passing-Bablok regression analysis. Implications of the conversion equation on epidemiological data were evaluated using KNHANES data from 2019-2021. Bias estimations determined using the Lipid Standardization Program (LSP) of the United States Centers for Disease Control and Prevention (CDC) enhanced the accuracy and comparability of the triglyceride results.

Results: Triglyceride concentrations measured via the glycerol non-blanking method were 10.7 mg/dL (0.12 mmol/L, 10.0%) higher than those from the glycerol blanking method, with a 9.9 mg/dL (0.11 mmol/L, 5.0%) difference at a concentration of 200 mg/dL (2.26 mmol/L, N=98). The conversion equation y (glycerol non-blanking, 2022)=11.94+0.99x (glycerol blanking, 2005-2021) changed the mean triglyceride concentrations of the KNHANES 2019-2021 data (N=16,015) from 123.7 mg/dL (1.40 mmol/L, 95% confidence interval [CI]: 122.2-125.1 mg/dL [1.38-1.41 mmol/L]) to 134.3 mg/dL (1.52 mmol/L, 95% CI: 132.9-135.8 mg/dL [1.50-1.53 mmol/L]). Since 2022, bias monitoring using the CDC's LSP has remained within a 5.0% limit.

Conclusions: KNHANES triglyceride values in 2022 (non-blanking) were substantially higher than those from 2005-2021 (blanking). Conversion equations helped effectively adjust 2005-2021 data. Researchers should consider adjusting the KNHANES triglyceride data based on their study characteristics.