Reference Values for Serum Lipid Profiles in Iranian Adults: A Spline-Based Quantile Regression Method

Background: Reference measurements are used to screen for abnormal blood lipids. The problem is that these reference values obtained in one population cannot be effective for another population. This study aimed to determine the reference values for blood lipids profiles in the population aged 25-64 years in Yazd. Methods: This descriptive study was based on the data of  Yazd Health Study (YaHS) on 3800 adults by cluster sampling. The data set included gender, age, total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), and  high-density lipoprotein-cholesterol (HDL-C). The linear percentile regression model and the generalized additive model for location, scale, and shape (GAMLSS) were fitted to the data and the reference values were predicted according to the regression coefficients. R-3.0.1 software was used for data analysis. Results: Refrence values for TC, LDL-C, and HDL-C were 109.43-275.72, 45.58-177.70, and 29.95-62.22 mg/dl. The trend of TC, TG, and LDL-C levels increased with age in both genders, but the trend of HDL-C in men decreased with age and remained almost constant in women. Conclusion: In this study, for the population of Yazd, reference values for blood lipids were different in both genders and age groups. Reference values for lipid profile increased in men and women with age.These findings can be used in both prevention and clinical decisions.