Background/Aims: We examined the association between diabetes duration and hyperuricemia in Korean subjects based on data from the Korea National Health and Nutrition Examination Survey (KNHANES). Methods: This cross-sectional study included 4,575 subjects aged 30 years and older with type 2 diabetes mellitus based on data from the KNHANES from 2016 to 2021. Hyperuricemia was defined as a serum uric acid level ≥ 7.0 mg/dL. Univariable and multivariable logistic regression models were used calculate adjusted odds ratios (ORs) and their 95% confidence intervals (CIs). Results: The mean age of subjects was 61.0 years, 56.5% were male, and the mean body mass index (BMI) was 25.6 kg/m2. Compared to those with diabetes duration 5 to < 10 years, those with shorter or longer diabetes duration had higher serum uric acid levels and higher prevalence of hyperuricemia. In multivariable logistic regression models, a U-shaped association between diabetes duration and hyperuricemia was observed after adjusting for age, sex, income, smoking status, alcohol consumption, regular exercise, and presence of hypertension, dyslipidemia, or chronic kidney disease. Compared to those with new-onset diabetes mellitus, the adjusted OR (95% CI) for hyperuricemia was 0.55 (0.38–0.82) in those with diabetes duration 5 to < 10 years. The results were consistent in subgroup analysis according to age, sex, BMI, and chronic kidney disease. Conclusions The U-shaped association between diabetes duration and hyperuricemia was observed in a representative sample of Korean adults.

Background: Psoriasis is acknowledged for its association with diabetes and obesity. However, the comprehension of the correlation between obesity and psoriasis risk in individuals with diabetes remains limited. Objective: We aimed to examine the association of body mass index and waist circumference (WC) with the risk of developing psoriasis in individuals with type 2 diabetes mellitus (T2DM). Methods: This retrospective cohort study utilized nationwide data for exploratory analysis.A total of 2,480,489 participants, all diagnosed with T2DM, were included. Results: Over a 6.77±1.69-year follow-up, 71,514 patients (2.88%) were diagnosed with psoriasis. Adjusting for multiple variables, the study revealed a J-shaped pattern association between BMI levels and the hazard ratio (HR) for psoriasis in patients with T2DM. A linear pattern relationship was observed regarding WC, with the highest WC group showing the most elevated HR (HR, 1.123; 95% confidence interval, 1.091–1.156). Conclusion Understanding the relationship between psoriasis risk and obesity in diabetic individuals holds the potential to enhance the management of patients with T2DM.

Objective: This study aimed to assess the association between exposure to gadolinium-based contrast agents (GBCAs) and the risk of parkinsonism according to the GBCA type. Materials and Methods: Individuals aged ≥40 years who underwent first-ever magnetic resonance imaging (MRI) examinations between 2011 and 2014 were identified from the Korean nationwide population-based health insurance claims database and followed up until 2022. Individuals were divided into those who underwent at least one GBCA-enhanced MRI, and those who underwent only non-enhanced MRI. GBCA-exposed individuals were further categorized into those exposed only to linear or macrocyclic GBCAs, after excluding those exposed to both types. The primary event of interest was allcause parkinsonism. Secondary events included all-cause parkinsonism requiring medication, Parkinson’s disease (PD), atypical parkinsonism, and secondary parkinsonism. Hazard ratios (HRs) were estimated using multivariable Cox proportional hazard regression models for exposure to linear and macrocyclic GBCAs, with the non-enhanced MRI group serving as a reference. The models were adjusted for age, sex, smoking status, alcohol consumption, regular exercise, body mass index, estimated glomerular filtration rate, and comorbidities. Subgroup analyses were performed according to age, sex, renal function, and history of cancer. Results: A total of 222,977 individuals were included in this study. Among them, 92,230, 48,335, and 82,412 individuals underwent non-enhanced, linear GBCA-enhanced, and macrocyclic GBCA-enhanced MRI, respectively. Exposure to linear GBCAs slightly increased the risk of all-cause parkinsonism (adjusted HR, 1.13 [97.5% confidence interval, 1.08–1.19]), while exposure to macrocyclic GBCAs did not increase the risk (adjusted HR, 1.00 [97.5% confidence interval, 0.95–1.05]).The results were similar for all-cause parkinsonism requiring medication, PD, and secondary parkinsonism, whereas no significant association was observed for atypical parkinsonism. Conclusion Exposure to linear GBCAs may slightly increase the risk of parkinsonism in adults, whereas exposure to macrocyclic GBCAs may not. Caution should be exercised when using linear GBCAs until further evidence emerges.

Purpose: Previous studies from mostly Western populations have suggested possible associations between obesity and melanoma risk. This study aimed to investigate associations between obesity status and melanoma using a nationwide cohort of Koreans. Materials and Methods: A total of 4,441,403 adults who received a national health examination in 2012 were included from the Korean National Health Insurance Service database, and followed until December 31, 2022. Obesity status was defined based on the body mass index at the baseline health examination. Cox proportional hazards analyses were performed to evaluate associations between obesity status and incident melanoma, with adjustment for confounders. Stratified analyses were performed by sex and menopausal status (in women). Results: Overall, melanoma risk increased according to obesity status (p for trend=0.024); adjusted hazard ratios (95% confidence intervals) for melanoma risk were 0.766 (0.438–1.340) in underweight; 1.292 (1.072–1.557) in overweight; 1.202 (1.002–1.442) in obesity; and 1.191 (0.798–1.778) in severe obesity compared to normal weight (reference). In stratified analyses, similar trends to those of the overall study population were observed among men and premenopausal women (p for trend=0.052 in men and 0.036 in premenopausal women). Among premenopausal women, the risk of melanoma increased linearly with obesity status. Meanwhile, among postmenopausal women, melanoma risk showed no significant difference or trend according to obesity status. Conclusion Overweight and obesity were associated with increased risk of melanoma in a population-based cohort of Koreans. Obese individuals, especially men and premenopausal women, may require more thorough prevention and screening strategies for melanoma.

Background/Aims: This study aimed to evaluate the impact of steatotic liver disease severity on the cumulative incidence of lung cancer utilizing data from the Korea National Health Insurance Service (NHIS). Methods: This study examined the risk of lung cancer in the general population in conjunction with the incidence of steatotic liver disease. The study population consisted of 3,261,438 individuals aged 20 years or older who underwent a general health examination in 2009. Results: Individuals with fatty liver index (FLI) of 30–59 exhibited a 1.08-fold increased risk of lung cancer (95% CI: 1.04–1.11), while FLI ≥ 60 was associated with a 1.22-fold elevated risk of lung cancer (95% CI: 1.17–1.28) compared to those with FLI < 30. The risk varied with smoking status; in current smokers, the adjusted HR for the FLI 30–59 group was 1.05 (95% CI: 1.00–1.10), while that in the FLI ≥ 60 group was 1.11 (95% CI: 1.04–1.18). In never- or past-smokers, the adjusted HR for the FLI 30–59 group was 1.10, and that for the FLI ≥ 60 group was 1.31. Subgroup analysis revealed an incidence rate of 1.06 per 1,000 person-years in the consistently high FLI group compared to 1.15 in those with improved FLI. Improving FLI over time was associated with a 0.93-fold decrease in lung cancer risk. Conclusions Our study demonstrated a correlational relationship between lung cancer incidence and the severity of steatotic liver disease as measured by FLI.

The number of large-scale epidemiological studies using administrative databases has rapidly increased in recent years. However, in observational studies, the outcomes of interest are heavily influenced by concurrent or pre-existing comorbidities, which act as confounders, and appropriate adjustment of comorbidities is essential to minimize bias. Although several comorbidity indices are available for this purpose, Charlson comorbidity index (CCI) is the most widely used one. The original version of the CCI was developed for use in longitudinal studies, to classify comorbidities that might alter the risk of mortality. It included 19 comorbidities, with each comorbidity having an assigned weight from 1 to 6; the total CCI score is a simple sum of the weights. Although the original CCI was based on a review of medical records, many modified versions have been proposed in subsequent studies using claims data. The CCI and its modified versions are used in virtually all clinical settings, including oncology, cardiology, respiratory care, emergency care, surgery, intensive care, and geriatrics. Appropriate use of a comorbidity index, such as the CCI, is necessary to minimize bias in observational studies in the era of increasing use of administrative data for healthcare research.

Background/Aims: This study aimed to evaluate the impact of steatotic liver disease severity on the cumulative incidence of lung cancer utilizing data from the Korea National Health Insurance Service (NHIS). Methods: This study examined the risk of lung cancer in the general population in conjunction with the incidence of steatotic liver disease. The study population consisted of 3,261,438 individuals aged 20 years or older who underwent a general health examination in 2009. Results: Individuals with fatty liver index (FLI) of 30–59 exhibited a 1.08-fold increased risk of lung cancer (95% CI: 1.04–1.11), while FLI ≥ 60 was associated with a 1.22-fold elevated risk of lung cancer (95% CI: 1.17–1.28) compared to those with FLI < 30. The risk varied with smoking status; in current smokers, the adjusted HR for the FLI 30–59 group was 1.05 (95% CI: 1.00–1.10), while that in the FLI ≥ 60 group was 1.11 (95% CI: 1.04–1.18). In never- or past-smokers, the adjusted HR for the FLI 30–59 group was 1.10, and that for the FLI ≥ 60 group was 1.31. Subgroup analysis revealed an incidence rate of 1.06 per 1,000 person-years in the consistently high FLI group compared to 1.15 in those with improved FLI. Improving FLI over time was associated with a 0.93-fold decrease in lung cancer risk. Conclusions Our study demonstrated a correlational relationship between lung cancer incidence and the severity of steatotic liver disease as measured by FLI.

Purpose: Smoking may have a protective role in developing ulcerative colitis (UC) but have the opposite effect on Crohn’s disease (CD). This study aimed to determine the risk of developing inflammatory bowel disease (IBD) according to smoking status and onset age of smoking. Materials and Methods: We collected data on the smoking experiences of participants aged 20–39 years who underwent biannual examinations provided by the Korean National Health Screening Program from 2009 to 2012. IBD diagnosis was identified using the National Health Insurance Service. The risk of IBD according to smoking status and onset age of smoking was analyzed after adjusting for major clinical variables. Results: During a median 10.59-year follow-up, the risk of UC in ex-smokers was significantly higher than that in non-smokers, and the earlier ex-smokers started smoking, the higher risk of UC [ex-smokers whose onset age of smoking was <20 years, adjusted hazard ratio (aHR) 1.928, 95% confidence interval (CI)=1.649–2.255; 20–24 years, aHR 1.728, 95% CI=1.541–1.939; 25–29 years, aHR 1.676, 95% CI=1.489–1.887; ≥30 years, aHR 1.226, 95% CI=1.010–1.486]. The risk of UC was significantly lower in current smokers whose onset age of smoking was 25–29 years than in non-smokers (aHR 0.825, 95% CI=0.709–0.959). The risk of CD did not differ according to smoking status and onset age of smoking. Conclusion Ex-smokers who started smoking at a young age have a high risk of UC, even after adjusting for the smoking amount.

Purpose: Smoking may have a protective role in developing ulcerative colitis (UC) but have the opposite effect on Crohn’s disease (CD). This study aimed to determine the risk of developing inflammatory bowel disease (IBD) according to smoking status and onset age of smoking. Materials and Methods: We collected data on the smoking experiences of participants aged 20–39 years who underwent biannual examinations provided by the Korean National Health Screening Program from 2009 to 2012. IBD diagnosis was identified using the National Health Insurance Service. The risk of IBD according to smoking status and onset age of smoking was analyzed after adjusting for major clinical variables. Results: During a median 10.59-year follow-up, the risk of UC in ex-smokers was significantly higher than that in non-smokers, and the earlier ex-smokers started smoking, the higher risk of UC [ex-smokers whose onset age of smoking was <20 years, adjusted hazard ratio (aHR) 1.928, 95% confidence interval (CI)=1.649–2.255; 20–24 years, aHR 1.728, 95% CI=1.541–1.939; 25–29 years, aHR 1.676, 95% CI=1.489–1.887; ≥30 years, aHR 1.226, 95% CI=1.010–1.486]. The risk of UC was significantly lower in current smokers whose onset age of smoking was 25–29 years than in non-smokers (aHR 0.825, 95% CI=0.709–0.959). The risk of CD did not differ according to smoking status and onset age of smoking. Conclusion Ex-smokers who started smoking at a young age have a high risk of UC, even after adjusting for the smoking amount.

Purpose: Cancer survivors are at increased risk of diabetes mellitus (DM). Additionally, the prevalence of obesity, which is also a risk factor for DM, is increasing in cancer survivors. We investigated the associations between weight change after cancer diagnosis and DM risk. Materials and Methods: This retrospective cohort study used data from the Korean National Health Insurance Service. Participants who were newly diagnosed with cancer from 2010 to 2016 and received national health screening before and after diagnosis were included and followed until 2019. Weight change status after cancer diagnosis was categorized into four groups: sustained normal weight, obese to normal weight, normal weight to obese, or sustained obese. Cox proportional hazard analyses were performed to examine associations between weight change and DM. Results: The study population comprised 264,250 cancer survivors. DM risk was highest in sustained obese (adjusted hazard ratios [aHR], 2.17; 95% confidence interval [CI], 2.08 to 2.26), followed by normal weight to obese (aHR, 1.66; 95% CI, 1.54 to 1.79), obese to normal weight (aHR, 1.29; 95% CI, 1.21 to 1.39), and then sustained normal weight group (reference). In subgroup analyses according to cancer type, most cancers showed the highest risks in sustained obese group. Conclusion Obesity at any time point was related to increased DM risk, presenting the highest risk in cancer survivors with sustained obesity. Survivors who changed from obese to normal weight had lower risk than survivors with sustained obesity. Survivors who changed from normal weight to obese showed increased risk compared to those who sustained normal weight. Our finding supports the significance of weight management among cancer survivors.