Sex differences in the relationship between serum total bilirubin and risk of incident metabolic syndrome in community-dwelling adults: Propensity score analysis using longitudinal cohort data over 16 years.

BACKGROUND: Research on identifiable risks for metabolic syndrome (MetS) is ongoing, and growing evidence suggests that bilirubin is a potent antioxidant and cytoprotective agent against MetS. However, there have been conflicting results on the association between bilirubin and MetS. Our study aimed to validate the association by separately stratifying data for men and women in a longitudinal prospective study. METHODS: Data were derived from the Korean Genome Epidemiology Study provided by the Korea Centers for Disease Control and Prevention. Data from 5,185 adults aged 40-69 years (3,089 men and 2,096 women) without MetS were analyzed. The participants were divided according to sex-specific quartiles of serum total bilirubin levels and followed up biennially for 16 years (until 2018). The log-rank test was used for obtaining the Kaplan-Meier curves of cumulative incidence of MetS according to sex-specific serum total bilirubin quartiles, and the hazard ratios (HRs) with 95% confidence intervals (CIs) for incident metabolic syndrome were analyzed with a multiple Cox proportional hazard regression analysis model, after propensity score matching for removing differences at baseline. RESULTS: With increasing serum total bilirubin quartiles, the incidence rate per 1000 person-years proportionally decreased in both men and women. After propensity score matching and adjusting for confounding variables, the HRs (95% CIs) for MetS of the highest quartile in reference to the lowest quartile were 1.00 (0.80-1.24) for men and 0.80 (0.65-0.99) for women. Higher quartiles of serum total bilirubin showed significantly lower cumulative incidence of MetS in women (log-rank test p = 0.009), but not in men (log-rank test p = 0.285). CONCLUSION: Serum total bilirubin levels were significantly inversely associated with MetS in women, but there was no significant association observed in men. Sex differences in the effects of serum total bilirubin should be noted when predicting incident MetS by sex in clinical settings.

Modified triglyceride-glucose index indices are reliable markers for predicting risk of metabolic dysfunction-associated fatty liver disease: a cross-sectional study.

Introduction: Metabolic dysfunction-associated fatty liver disease (MAFLD) is newly proposed nomenclature, and its diagnosis involves an algorithm that can be complicated and impractical for clinicians in real-world clinical settings. Thus, we investigated the association between MAFLD and modified triglyceride-glucose index (TyG) indices to find a more concise, feasible method for predicting MAFLD in everyday clinical care. Methods: Data were obtained from people who voluntarily underwent health check-ups at the Health Promotion Centre of Gangnam Severance Hospital, Yonsei University College of Medicine, from January 2017 to October 2020. Four indices were analyzed: TyG-body to mass index (BMI), TyG-waist circumference (WC), TyG, and the fatty liver index (FLI). The odds ratios for MAFLD according to each index were calculated using multiple logistic regression analyses, and the receiver operating characteristics curve (ROC) and area under the ROC were obtained to find the predictive powers of each index. Results: The final number of study participants was 22,391, 8,246 with MAFLD and 14,145 without MAFLD. The odds ratios (95% confidence intervals) from TyG-WC and TyG-BMI after adjusting for confounding variables were 12.484 (9.962-15.644) and 12.494 (9.790-15.946), respectively, for quartile 2, 54.332 (43.131-68.442) and 51.580 (40.495-65.699) for quartile 3, and 165.804 (130.243-211.076) and 128.592 (100.601-164.371) for quartile 4. The area under the ROC curve values for TyG-WC and TyG-BMI were 0.862 (0.857-0.867) and 0.867 (0.862-0.872), respectively. Conclusion: The modified TyG indices are highly reliable markers for predicting MAFLD that clinicians can easily and practically apply in everyday, real-world, clinical care settings.

Long-Term Adverse Effects of Cigarette Smoking on the Incidence Risk of Metabolic Syndrome With a Dose-Response Relationship: Longitudinal Findings of the Korean Genome and Epidemiology Study Over 12 Years.

OBJECTIVE: To investigate the association between the intensity and cumulative dose of cigarette smoking and incidence risk of metabolic syndrome (MetS) in a longitudinal prospective study over 12 years of follow-up. METHODS: This study included 3151 men aged 40 to 69 years from the Korean Genome and Epidemiology Study. MetS was defined as proposed by the Joint Interim Statement of the Circulation 2009 report. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) for incidence risk of MetS were calculated from 2 separate perspectives: (1) number of cigarettes smoked per day (intensity) and (2) total number of cigarettes smoked over a person's lifetime (cumulative dose) using multiple logistic regression analyses. RESULTS: In comparison with never smokers, the HRs (95% CIs) were 0.97 (0.78-1.21) for former smokers and 1.50 (1.07-2.01) with 0 to 9 cigarettes per day, 1.66 (1.34-2.06) with 10 to 19 cigarettes per day, and 1.75 (1.34-2.29) with ≥20 cigarettes per day for current smokers after adjusting for confounding variables. Similar positive dose-response relationships were also observed when the cumulative dose of cigarette smoking was categorized into former and current smokers, with subcategories of <20 and >20 pack-years (PYs). The HRs (95% CIs) were 0.99 (0.77-1.23) for <20 PYs and 0.99 (0.77-1.28) for ≥20 PYs for former smokers and 1.63 (1.32-2.02) for <20 PYs and 1.67 (1.30-2.14) for ≥20 PYs for current smokers after adjusting for the same covariables. CONCLUSION: Cigarette smoking intensity and cumulative dose were both found to be positively associated with the incidence risk of MetS in men.