Background: The association of metabolic syndrome and its components with the risk of thyroid cancer is unclear. Thus, we conducted a large-scale, nationwide, population-based, cohort study to investigate this relationship. Methods: We studied 9,890,917 adults without thyroid cancer from the Korean National Health Insurance health checkup database from January 1 to December 31, 2009. Individuals with at least three of the following five components were diagnosed with metabolic syndrome: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein-cholesterol levels, elevated blood pressure, and hyperglycemia. Multivariate Cox proportional hazards models were used to estimate thyroid cancer risk. Results: During the average 7.2 years of follow-up, 77,133 thyroid cancer cases were newly identified. The thyroid cancer risk was higher in the metabolic syndrome group than in the nonmetabolic syndrome group (hazard ratio [HR] 1.15 [95% confidence interval, CI 1.13–1.17]). The association between metabolic syndrome and thyroid cancer risk was significant in the obese group (HR 1.10 [CI 1.07–1.13]) and not in the nonobese group (HR 1.002 [CI 0.98–1.03]). The effect of metabolic syndrome on the risk of thyroid cancer differs according to obesity ( p for interaction = 0.017). People with all five components of metabolic syndrome had a 39% higher risk than those without any components (HR 1.39 [CI 1.33–1.44]). The higher risk of thyroid cancer in people with all five components was significant in the obese group (HR 1.29 [CI 1.21–1.38]), but not in the nonobese group (HR 1.06 [CI 0.98–1.14]). There was a significant interaction between the number of metabolic syndrome components and obesity ( p for interaction <0.0001). For the combined effect of obesity and metabolic syndrome on the risk of thyroid cancer, obese men with metabolic syndrome had the highest risk of thyroid cancer compared with those without (HR 1.58 [CI 1.52–1.64]), but obese women with metabolic syndrome did not. Conclusions: Metabolic syndrome was associated with an increased risk of thyroid cancer in the Korean general population. Metabolic syndrome had a more significant risk of thyroid cancer in the obese group. Metabolic syndrome and obesity were associated with a higher risk of thyroid cancer in men but not in women.

Smoking traditionally has not been considered as a cause of bronchiectasis. However, few studies have evaluated the association between smoking and bronchiectasis. This study aimed to investigate the association between smoking status and bronchiectasis development in young adults. This study included 6,861,282 adults aged 20–39 years from the Korean National Health Insurance Service database 2009–2012 who were followed-up until the date of development of bronchiectasis, death, or 31 December 2018. We evaluated the incidence of bronchiectasis according to smoking status. During a mean of 7.4 years of follow-up, 23,609 (0.3%) participants developed bronchiectasis. In multivariable Cox regression analysis, ex-smokers (adjusted hazard ratio (aHR) = 1.07, 95% confidence interval (CI) = 1.03–1.13) and current-smokers (aHR = 1.06, 95% CI = 1.02–1.10) were associated with incident bronchiectasis, with the highest HR in ≥ 10 pack-years current smokers (aHR = 1.12, 95% CI = 1.06–1.16). The association of smoking with bronchiectasis was more profound in females than in males (p for interaction < 0.001), in younger than in older participants (p for interaction = 0.036), and in the overweight and obese than in the normal weight or underweight (p for interaction = 0.023). In conclusion, our study shows that smoking is associated with incident bronchiectasis in young adults. The association of smoking with bronchiectasis development was stronger in females, 20–29 year-olds, and the overweight and obese than in males, 30–40-year-olds, and the normal weight or underweight, respectively.

Background: Meta‐analyses of large clinical trials investigating SGLT2 (sodium‐glucose cotransporter‐2) inhibitors have suggested their protective effects against atrial fibrillation in patients with type 2 diabetes. However, the results were predominantly driven from trials involving dapagliflozin. Methods and Results: We used a nationwide, population‐based cohort of patients with type 2 diabetes who initiated either dapagliflozin or empagliflozin between May 2016 and December 2018. An active‐comparator, new‐user design was used, and the 2 groups of patients were matched using propensity scores. The primary outcome was incident nonvalvular atrial fibrillation, which was analyzed using both the main intention‐to‐treat and sensitivity analysis that censored patients who skipped their medications for ≥30 days. Men ≥55 years of age and women ≥60 years of age with ≥1 traditional risk factor or those with established cardiovascular disease were categorized as high cardiovascular risk group. Patients not included in the high‐risk group were categorized as low risk. After 1:1 propensity‐score matching, a total of 137 928 patients (mean age, 55 years; 58% men) were included and followed up for 2.2±0.6 years. The risk of incident atrial fibrillation was significantly lower in the dapagliflozin group in both the main (hazard ratio [HR], 0.885 [95% CI, 0.789–0.992]) and sensitivity analyses (HR, 0.835 [95% CI, 0.719–0.970]). Notably, this was consistent in both the low and high cardiovascular risk groups. There was no effect modification by age, sex, body mass index, duration of diabetes, or renal function. Conclusions: This real‐world, population‐based study demonstrates that patients with type 2 diabetes using dapagliflozin may have a lower risk of developing nonvalvular atrial fibrillation than those using empagliflozin.

Purpose: Hepatitis B virus (HBV) infection and metabolic syndrome (MS) are known independent risk factors for hepatocellular carcinoma (HCC) and other extrahepatic organ malignancies. The purpose of this study was to investigate whether MS and HBV have synergistic effects on cancers and to examine whether increasing the number of MS components could lead to higher risk of cancer development. Materials and Methods: We evaluated data from 1,504,880 HBV-infected adults who underwent a regular HCC screening program provided by the Korean National Health Insurance Service between 2009 and 2016. Results: The prevalence of MS in Korean HBV patients was 38.7% (582,449/1,504,880). Among individuals with HBV infection, the presence of MS was associated with an increased risk for the majority of malignancies except for HCC (HR = 0.862, p-value < 0.05). The presence of a higher number of MS components was associated with a significantly increased risk of developing cancers in most organs; only HCC was negatively associated with an increasing number of MS components (p < 0.01). Conclusions: Our data show that the presence of MS increases the risk for most malignancies, excluding HCC. Moreover, we found that as the number of MS components increased, the risk for most cancers also increased; this trend was reversed in HCC.

Weight variability has known as a risk factor for cardiovascular events and mortality. However, its effect on end-stage renal disease (ESRD) development remains controversial. We investigated the relationship between weight change and ESRD risk. Overall, 97,029 patients with DM aged >20 years were selected from the Korean National Health Screening Program 2009–2012. Weight change was defined as differences in body weight from the index year to 2 years later. Newly diagnosed ESRD was observed until 2017 end. Over a 5.1-year median follow-up period, ESRD was newly diagnosed in 7932 (4.81%) DM patients. BMI < 18.5 kg/m² and waist circumferences 100/95 cm were ESRD risk factors. ESRD risk increased with increasing weight change; ≥10% weight loss (hazard ratio [HR], 1.247) followed by ≥10% weight gain (1.247) was associated with a higher HR than ≤5% weight change after adjusting for several confounding factors. The association between weight change and ESRD risk in a subgroup analysis was significantly stronger in patients aged <65 years, without proteinuria, with BMI ≥ 25, with DM duration 10% was associated with the fastest decline in renal function.

Kim K, et al. J Lipid Atheroscler. 2021 Sep;10(3):291-302. https://doi.org/10.12997/jla.2021.10.3.291