Urinary Cotinine-Verified Smoking Status and Serum Lipid Profiles and Lipid Ratios in Korean Older Adults: A Nationwide Cross-Sectional Study

Background: Serum lipid profile is an important factor in predicting the risk of cardiovascular disease, and smoking is considered to affect serum lipid levels adversely by altering lipid metabolism. Although traditional lipid profiles are important in patient evaluation for predicting the risk of cardiovascular disease, the clinical significance of lipid ratios has recently gained attention as well. We aimed to investigate the relationship between smoking and serum lipid profiles and ratios in Korean older adults.METHODS: This cross‐sectional analysis used a nationally representative sample from the 2014–2016 Korea National Health and Nutrition Examination Survey (KNHANES). In total, 4,349 participants aged ≥60 years with urine cotinine values were included. The outcome was a comparison of unfavorable lipid profiles/ratios in respect to urine cotinine-verified smoking status (urine cotinine level ≥50 ng/mL), and quantification of the associations between smoking and unfavorable lipid profiles/ratios using multivariable logistic regression analyses. In our analyses, the lowest quartile (Q1) of high-density lipoprotein cholesterol (HDL-C), and the highest quartile (Q4) of low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and total cholesterol (TC), and their ratios (TC/HDL-C, LDL-C/HDL-C, and TG/HDL-C) were considered as unfavorable.Results: The percentages of unfavorable lipid profiles/ratios except for serum TC and LDL-C were significantly higher in the urine cotinine-verified smoker group. The odds ratios (ORs) and 95% confidence intervals (CIs) of urine cotinine-verified smokers for the Q1 of HDL-C and for the Q4 of TG, TC/HDL-C, LDL-C/HDL-C, and TG/HDL-C were 1.67 (95% CI: 1.29–2.17) and 1.49 (95% CI: 1.14–1.96), 1.50 (95% CI: 1.14–1.97), 1.44 (95% CI: 1.10–1.89), and 1.75 (95% CI: 1.35–2.28), respectively.Conclusion: Urine cotinine-verified smoking status was significantly associated with unfavorable serum lipid profiles/ratios in Korean older adults.