Background: Firefighters are exposed to shift work, as well as unpredictable emergency calls and traumatic events, which can lead to sleep problems. This study aimed to investigate the risk of insomnia by work schedule instability in Korean firefighters. Methods: This study used the Insomnia Severity Index to assess the insomnia in firefighters. The work schedule stability was classified with the frequency of the substitute work and the timing of notification for work schedule changes. Logistic regression analysis was used to assess the adjusted odds ratio of insomnia by work schedule stability with covariates including sex, age, education, smoking, alcohol, caffeine intake, shift type, job, and underlying conditions. Results: Of the 8,587 individuals, 751 (8.75%) had moderate to severe insomnia (Insomnia Severity Index ≥ 15). The prevalence of insomnia was statistically significantly higher as the frequency of substitute work increased: <1 time per month (6.8%), 1–2 times (9.5%), 3–5 times (13.4%), and more than 5 times (15.7%) (p < 0.001). Additionally, the prevalence of insomnia was statistically significantly higher when the timing of the schedule change notification was urgent or irregular: no change or several weeks before (5.4%), several days before (7.9%), one day before or on the day (11.2%), irregularly notification (11.6%) (p < 0.001). In comparison to the group with good frequency of the substitute work/good timing of schedule change notification group, the adjusted odds ratios of insomnia were 1.480 (95% confidence interval [CI]: 1.237–1.771) for Good/Bad group, 1.862 (95% CI: 1.340–2.588) for Bad/Good group, and 1.885 (95% CI: 1.366–2.602) for Bad/Bad group. Conclusions Work schedule instability was important risk factor of insomnia in firefighters. It suggests that improving the stability of work schedules could be a key strategy for reducing sleep problems in this occupational group.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: Firefighters are exposed to shift work, as well as unpredictable emergency calls and traumatic events, which can lead to sleep problems. This study aimed to investigate the risk of insomnia by work schedule instability in Korean firefighters. Methods: This study used the Insomnia Severity Index to assess the insomnia in firefighters. The work schedule stability was classified with the frequency of the substitute work and the timing of notification for work schedule changes. Logistic regression analysis was used to assess the adjusted odds ratio of insomnia by work schedule stability with covariates including sex, age, education, smoking, alcohol, caffeine intake, shift type, job, and underlying conditions. Results: Of the 8,587 individuals, 751 (8.75%) had moderate to severe insomnia (Insomnia Severity Index ≥ 15). The prevalence of insomnia was statistically significantly higher as the frequency of substitute work increased: <1 time per month (6.8%), 1–2 times (9.5%), 3–5 times (13.4%), and more than 5 times (15.7%) (p < 0.001). Additionally, the prevalence of insomnia was statistically significantly higher when the timing of the schedule change notification was urgent or irregular: no change or several weeks before (5.4%), several days before (7.9%), one day before or on the day (11.2%), irregularly notification (11.6%) (p < 0.001). In comparison to the group with good frequency of the substitute work/good timing of schedule change notification group, the adjusted odds ratios of insomnia were 1.480 (95% confidence interval [CI]: 1.237–1.771) for Good/Bad group, 1.862 (95% CI: 1.340–2.588) for Bad/Good group, and 1.885 (95% CI: 1.366–2.602) for Bad/Bad group. Conclusions Work schedule instability was important risk factor of insomnia in firefighters. It suggests that improving the stability of work schedules could be a key strategy for reducing sleep problems in this occupational group.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: Firefighters are exposed to shift work, as well as unpredictable emergency calls and traumatic events, which can lead to sleep problems. This study aimed to investigate the risk of insomnia by work schedule instability in Korean firefighters. Methods: This study used the Insomnia Severity Index to assess the insomnia in firefighters. The work schedule stability was classified with the frequency of the substitute work and the timing of notification for work schedule changes. Logistic regression analysis was used to assess the adjusted odds ratio of insomnia by work schedule stability with covariates including sex, age, education, smoking, alcohol, caffeine intake, shift type, job, and underlying conditions. Results: Of the 8,587 individuals, 751 (8.75%) had moderate to severe insomnia (Insomnia Severity Index ≥ 15). The prevalence of insomnia was statistically significantly higher as the frequency of substitute work increased: <1 time per month (6.8%), 1–2 times (9.5%), 3–5 times (13.4%), and more than 5 times (15.7%) (p < 0.001). Additionally, the prevalence of insomnia was statistically significantly higher when the timing of the schedule change notification was urgent or irregular: no change or several weeks before (5.4%), several days before (7.9%), one day before or on the day (11.2%), irregularly notification (11.6%) (p < 0.001). In comparison to the group with good frequency of the substitute work/good timing of schedule change notification group, the adjusted odds ratios of insomnia were 1.480 (95% confidence interval [CI]: 1.237–1.771) for Good/Bad group, 1.862 (95% CI: 1.340–2.588) for Bad/Good group, and 1.885 (95% CI: 1.366–2.602) for Bad/Bad group. Conclusions Work schedule instability was important risk factor of insomnia in firefighters. It suggests that improving the stability of work schedules could be a key strategy for reducing sleep problems in this occupational group.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Purpose: The treatment of male breast cancer (MBC) has been extrapolated from female breast cancer (FBC) because of its rarity despite their different clinicopathologic characteristics. We aimed to investigate the distribution of intrinsic subtypes based on immunohistochemistry, their clinical impact, and treatment pattern in clinical practice through a multicenter study in Korea. Materials and Methods: We retrospectively analyzed clinical data of 248 MBC patients from 18 institutions across the country from January 1995 to July 2016. Results: The median age of MBC patients was 63 years (range, 25 to 102 years). Among 148 intrinsic subtype classified patients, 61 (41.2%), 44 (29.7%), 29 (19.5%), and 14 (9.5%) were luminal A, luminal B, human epidermal growth factor receptor 2, and triple-negative breast cancer, respectively. Luminal A subtype showed trends for superior survival compared to other subtypes. Most hormone receptor-positive patients (166 patients, 82.6%) received adjuvant endocrine treatment. Five-year completion of adjuvant endocrine treatment was associated with superior disease-free survival (DFS) in patients classified with an intrinsic subtype (hazard ratio [HR], 0.15; 95% confidence interval [CI], 0.04 to 0.49; p=0.002) and in all patients (HR, 0.16; 95% CI, 0.05 to 0.54; p=0.003). Conclusion Distribution of subtypes of MBC was similar to FBC and luminal type A was most common. Overall survival tended to be improved for luminal A subtype, although there was no statistical significance. Completion of adjuvant endocrine treatment was associated with prolonged DFS in intrinsic subtype classified patients. MBC patients tended to receive less treatment. MBC patients should receive standard treatment according to guidelines as FBC patients.

Purpose: We aimed to investigate factors that correlate with fecal calprotectin (FC) levels in children and adolescents with colorectal polyps. Methods: Pediatric patients aged <19 years who underwent colonoscopic polypectomy for a juvenile polyps (JPs) and FC tests were simultaneously conducted in a multicenter, retrospective study. Baseline demographics, colonoscopic and histological findings, and laboratory tests, including FC levels, were investigated. Correlations between the factors were investigated, and linear regression analysis revealed factors that correlated with FC levels. FC levels measured after polypectomies were investigated and the FC levels pre- and post-polypectomies were compared. Results: A total of 33 patients were included in the study. According to Pearson correlation analysis, the polyp size was the only factor that showed a statistically significant correlation with FC levels (r=0.75, p<0.001). Furthermore, according to the multivariate linear regression analysis, polyp size was the only factor that showed a statistically significant correlation with FC levels (adjusted R2=0.5718, β=73.62, p<0.001). The median FC level was 400 mg/ kg (interquartile range [IQR], 141.6–1,000 mg/kg), and the median polyp size was 14 mm (IQR, 9–20 mm). Nineteen patients underwent post-polypectomy FC tests. FC levels showed a significant decrease after polypectomy from a median of 445.2 mg/kg (IQR, 225–1,000) to 26.5 mg/kg (11.5–51) ( p<0.001). Conclusion FC levels significantly correlated with polyp size in children and adolescents with JPs.

Purpose: The characteristic topography and climate often affect the occurrence of large-scale wildfires in the Eastern Gangwon-do region of Korea. However, there are no studies on the health effects of these wildfires in Korea. This study aimed to analyze the differences in medical use between a wildfire-affected area and an adjacent non-affected area before and after a wildfire in 2019 in Gangwon-do, Korea. Materials and Methods: We used medical usage data from the Korean National Health Insurance Corporation. Rates of medical use were determined for citizens of a wildfire-affected area in the Eastern Yeongdong region and a non-affected area in the Western Yeongseo region. Logistic regression analysis was performed considering an increase in medical use per individual as a dependent variable; age, sex, income, smoking, drinking, and exercise were included as confounding variables. Results: The odds ratio for medical use in Yeongdong region increased significantly after 3 days, 3 months, and 1 year after a fire occurred, compared with Yeongseo region. Conclusion The results of this study confirmed that the use of medical care increased for residents of a wildfire-affected area, compared with those of an adjacent non-affected area. This is the first study on the relationship between wildfires and inpatient medical use in Korea.