Woncheol Lee

Purpose Evidence linking particulate matter (PM) to low-density lipoprotein cholesterol (LDL-C) remains inconsistent. We examined associations of short- (1–7 days), mid- (1–6 months), and long-term (1–5 years) PM₁₀ and PM_2.5 exposures with elevated LDL-C (≥ 160 mg/dL or medication use) in Korean adults. Methods In this cross-sectional analysis of 14,867 Korean adults from the 2016–2022 the Korea National Health and Nutrition Examination Survey (KNHANES), a nationally representative survey. We used complex samples logistic regression, to estimate odds ratios (ORs) per interquartile range increase in PM, adjusting for sociodemographic, behavioral, occupational, and clinical covariates. Results Both PM₁₀ and PM_2.5 were positively associated with elevated LDL-C across most windows. In fully adjusted models, PM₁₀ ORs ranged from 1.143 to 1.236. For PM_2.5, ORs ranged from 1.097 to 1.181. Associations remained robust after adjusting for lifestyle, adiposity, and chronic conditions. Conclusion Short-, mid-, and long-term PM exposures were consistently associated with elevated LDL-C levels. These findings suggest PM is associated with alterations in lipid metabolism through acute and chronic pathways, highlighting air pollution as an environmental factor associated with dyslipidemia and cardiometabolic risk.

Metabolic dysfunction–associated steatotic liver disease (MASLD) is the most common chronic liver disorder worldwide and is increasingly recognized as a multisystem disease that elevates cardiovascular disease (CVD) risk. Liver fibrosis, rather than steatosis itself, is considered the primary determinant of prognosis in MASLD. The Fibrosis-4 (FIB-4) index, a simple noninvasive fibrosis score, has been linked to adverse hepatic outcomes, but its value for predicting subclinical atherosclerosis remains unclear. We investigated whether time-updated FIB-4 predicts coronary artery calcification (CAC) progression in a large cohort of asymptomatic Korean adults. A total of 60,445 participants who underwent repeated coronary computed tomography and liver ultrasonography during health examinations between 2012 and 2023 were included. CAC progression, defined as incident CAC (Agatston score ≥ 1) or a significant increase in existing CAC, was assessed using time-dependent Cox regression models. Elevated FIB-4 was significantly associated with higher risk of CAC progression among participants with MASLD, independent of established CVD risk factors. In stratified analyses, the association was stronger in men and in individuals older than 40 years. These findings indicate that the time-updated FIB-4 index shows a modest association with subclinical atherosclerosis progression, primarily among men aged ≥ 40 years with MASLD, and may serve as an accessible marker reflecting subclinical cardiovascular risk rather than a validated predictor of risk stratification improvement.

Metabolic dysfunction–associated steatotic liver disease (MASLD) is a major public health concern. However, its relationship with the long-term mortality risk remains underexplored in the general population. We aimed to examine the association between liver fibrosis, assessed using the age-adjusted Fibrosis-4 (FIB-4) residual index, and all-cause and cardiovascular mortality in individuals with MASLD. This cohort study included 134,686 adults diagnosed with MASLD via ultrasonography and metabolic abnormalities during health screenings at two Korean centers between 2002 and 2022. The participants were followed up for mortality outcomes using the National Death Registry. The FIB-4 index was calculated from age, AST, ALT, and platelet count adjusted for age using residual modeling. Cox proportional hazards models were used to estimate the hazard ratios (HRs) for all-cause and cardiovascular mortality, adjusting for sociodemographic, behavioral, and clinical covariates. Age-stratified analyses were also performed. During a mean follow-up of 11.2 years, 2,129 all-cause and 348 cardiovascular deaths occurred. A higher age-adjusted FIB-4 index was associated with increased risk of all-cause mortality (HR 1.489, 95% CI 1.353–1.639) and cardiovascular mortality (HR 1.478, 95% CI 1.175–1.860). These associations persisted after adjustment. In stratified analyses, all-cause mortality associations were significant in both age groups, whereas cardiovascular mortality was significant only in those aged > 39 years. The age-adjusted FIB-4 index was independently associated with increased risk of all-cause and cardiovascular mortality in patients with MASLD. Assessing liver fibrosis using FIB-4 may provide prognostic information beyond traditional cardiometabolic risk factors in this population.

Long working hours are increasingly recognized as a significant occupational hazard linked to various adverse health outcomes. This study aimed to assess how prolonged working hours relate to the subsequent development of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic and alcohol-associated liver disease (MetALD), based on a newly proposed classification system. We analyzed data from 117,354 Korean employees who underwent at least two abdominal ultrasound examinations between 2012 and 2023. Long working hours referred to a weekly workload of at least 60 hours. The primary outcome was the incidence of steatotic liver disease, categorized as MASLD or MetALD. A total of 28,361 new cases were identified over 627,094 person-years of follow-up. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Participants working ≥60 hours per week had a higher risk of developing MASLD (adjusted HR 1.17, 95% CI 1.03–1.32) and MASLD+MetALD (adjusted HR 1.18, 95% CI 1.05–1.33) compared with those working 35–59 hours per week. Subgroup analyses indicated that the association was especially pronounced among individuals aged ≤47 years and in men. These results suggest that prolonged working hours contribute to an increased risk of MASLD and MASLD+MetALD, particularly in younger and male populations, emphasizing the importance of occupational health interventions.

Non-alcoholic fatty liver disease (NAFLD) is a relatively common disease, and preventing its occurrence is important for both individual health and reducing social costs. Shift work is reported to have several negative effects on health. An association has been observed between NAFLD and both sleep time and quality; however, this association remains unclear in night shift workers. We aimed to evaluate the relationship between shift work and the incidence of NAFLD. Overall, 45,149 Korean workers without NAFLD were included at baseline. NAFLD was defined as the presence of a fatty liver observed on ultrasonography without excessive alcohol use. incidence rate ratios for incident NAFLD were estimated using negative binomial regression according to age groups (20s, 30s, 40s, and 50s). In the 20s age group, shift work showed a significant incidence rate ratio (IRR) for NAFLD in all models. After adjusting for all variables, the IRR (95% confidence interval) was 1.24 (1.08–1.43) in the 20s age group. In their 20s, a significant association between shift work and incident NAFLD was consistently observed among women and workers with poor sleep quality. In this large-scale cohort study, shift work was significantly associated with the development of NAFLD among young workers in their 20s.

Lee J, et al. Ann Occup Environ Med. 2024 Jan;36:e1. https://doi.org/10.35371/aoem.2024.36.e1

Introduction: Occupational health nurses (OHNs) in South Korea who visit the workplace periodically could play a key role in smoking cessation. It would be helpful to assess their understanding of smoking hazards and smoking cessation methods to encourage them to provide smoking intervention...

Shift work has adverse health effects such as diabetes, cardiovascular disease, sleep disturbance, depression, and breast cancer. Gastro-esophageal reflux disease (GERD) results in lesions such as reflux esophagitis (RE) and Barrett’s esophagus. This study investigated the association between shift work and RE. A cohort study was conducted with 140,553 participants who were followed up at least once from 2012 to 2018. Type of working and shift types were collected using standardized questionnaires. Esophagogastroduodenoscopy (EGD) was performed by experienced endoscopists who were blinded to the aims of this study. According to the Los Angeles classification, RE was categorized based on the extent of esophageal mucosal breaks. During the 469,217.2 person-years of follow-up, 35,185 participants developed incident cases of RE. The multivariable adjusted hazard ratio (95% confidence intervals) for incident cases comparing shift work to fixed day work was 1.09 (1.04–1.13). This association was more strongly observed in the younger age group (18–39 years old) and the female group. In conclusion, shift work was significantly associated with the incidence of RE. Particularly, the results were more significant in the younger and female groups.