Background/Aims: The long-term course of Crohn’s disease (CD) has never been evaluated in non-Caucasian population-based cohorts. The aim of the present study was to evaluate the longterm prognosis of Korean CD patients in the well-defined population-based Songpa-Kangdong inflammatory bowel disease cohort. Methods: Outcomes of disease and their predictors were evaluated for 418 patients diagnosed with CD between 1986 and 2015. Results: During a median of 123 months, systemic corticosteroids, thiopurines, and anti-tumor necrosis factor (TNF) agents were administered to 58.6%, 81.3%, and 37.1% of patients, respectively. Over time, the cumulative probability of starting corticosteroids significantly decreased (p=0.001), whereas that of starting thiopurines and anti-TNFs significantly increased (both p<0.001). The cumulative probability of behavioral progression was 54.5% at 20 years, and it significantly decreased during the anti-TNF era. Intestinal resection was required for 113 patients (27.0%). The cumulative probabilities of intestinal resection at 1, 5, 10, 20, and 25 years after CD diagnosis were 12.7%, 16.5%, 23.8%, 45.1%, and 51.2%, respectively. Multivariable Cox regression analysis identified stricturing behavior at diagnosis (adjusted hazard ratio [aHR], 2.70; 95% confidence interval [CI], 1.55 to 4.71), penetrating behavior at diagnosis (aHR, 11.15; 95% CI, 6.91 to 17.97), and diagnosis of CD during the anti-TNF era (aHR, 0.51; 95% CI, 0.35 to 0.76) as independently associated with intestinal resection. The standardized mortality ratio among CD patients was 1.36 (95% CI, 0.59 to 2.68). Conclusions The long-term prognosis of Korean patients with CD is at least as good as that of Western CD patients, as indicated by the low intestinal resection rate. Moreover, behavioral progression and intestinal resection rates have decreased over the past 3 decades.

Background/Aims: Ascertaining the prevalence of isolated nocturnal hypertension (INHT) in the general population and identifying the characteristics of patients with INHT may be important to determine patients who should receive 24- hour ambulatory blood pressure (BP) measurements. This study aimed to evaluate the prevalence and characteristics of INHT in the general population. Methods: Of 1,128 participants (aged 20 to 70 years), we analyzed 823 who had valid 24-hour ambulatory BP measurements and were not on antihypertensive drug treatment. Results: The prevalence of INHT in the study was 22.8%. Individuals with INHT had a higher office, 24-hour, and daytime and nighttime ambulatory systolic and diastolic BPs compared to individuals with sustained day-night normotension. INHT was more prevalent in individuals with masked hypertension (MH) than in those with sustained hypertension (59.8% vs. 15.6%, p < 0.001). Among individuals with INHT, 92.6% had MH. Among individuals with office BP-based prehypertension, 34.5% had both INHT and MH. The prevalence of INHT was highest in individuals with office BP-based prehypertension. INHT was an independent determinant of MH after adjustment for age, sex, body mass index, diabetes, low-density-lipoprotein cholesterol, 24-hour systolic and diastolic BP, systolic and diastolic BP dipping, and systolic and diastolic BP non-dipping. Conclusions The present study showed that INHT is not uncommon and is a major determinant of MH. Our findings strongly suggest the use of 24-hour ambulatory BP measurement for individuals within the prehypertension range of office BP owing to the high prevalence of INHT and MH in this population.

Background/Aims: Ascertaining the prevalence of isolated nocturnal hypertension (INHT) in the general population and identifying the characteristics of patients with INHT may be important to determine patients who should receive 24- hour ambulatory blood pressure (BP) measurements. This study aimed to evaluate the prevalence and characteristics of INHT in the general population. Methods: Of 1,128 participants (aged 20 to 70 years), we analyzed 823 who had valid 24-hour ambulatory BP measurements and were not on antihypertensive drug treatment. Results: The prevalence of INHT in the study was 22.8%. Individuals with INHT had a higher office, 24-hour, and daytime and nighttime ambulatory systolic and diastolic BPs compared to individuals with sustained day-night normotension. INHT was more prevalent in individuals with masked hypertension (MH) than in those with sustained hypertension (59.8% vs. 15.6%, p < 0.001). Among individuals with INHT, 92.6% had MH. Among individuals with office BP-based prehypertension, 34.5% had both INHT and MH. The prevalence of INHT was highest in individuals with office BP-based prehypertension. INHT was an independent determinant of MH after adjustment for age, sex, body mass index, diabetes, low-density-lipoprotein cholesterol, 24-hour systolic and diastolic BP, systolic and diastolic BP dipping, and systolic and diastolic BP non-dipping. Conclusions The present study showed that INHT is not uncommon and is a major determinant of MH. Our findings strongly suggest the use of 24-hour ambulatory BP measurement for individuals within the prehypertension range of office BP owing to the high prevalence of INHT and MH in this population.

Background/Aims: We aimed to evaluate the clinical characteristics and long-term prognosis of elderly-onset ulcerative colitis (EOUC) in Korean patients over a 30-year period using a wellestablished population-based cohort in the Songpa-Kangdong district of Seoul, Korea. Methods: Clinical characteristics and prognosis were compared between two groups: EOUC,defined as UC diagnosed in individuals aged ≥60 years and non-EOUC (N-EOUC), defined asUC diagnosed in individuals aged 18 to 59 years. Results: We identified 99 patients with EOUC (10.3%) and 866 patients with N-EOUC (89.7%) between 1986 and 2015. During the median follow-up of 104.5 months, the overall exposure tomedications was comparable between patients with EOUC and N-EOUC (p=0.091 for corticosteroids, p=0.794 for thiopurines, and p=0.095 for anti-tumor necrosis factor agents). The cumula-tive risks of disease outcomes were also comparable between patients with EOUC and N-EOUC (22.4% vs 30.4% for proximal disease extension [p=0.351], 11.9% vs 18.1% for hospitalization [p=0.240], and 2.3% vs 1.8% for colectomy [p=0.977]) at 10 years after diagnosis. Multivariate Cox regression analysis revealed that corticosteroid use at diagnosis was an independent predic-tor of proximal disease extension (hazard ratio [HR], 6.216; 95% confidence interval [CI], 1.314 to 28.826) and hospitalization (HR, 11.241; 95% CI, 3.027 to 41.742) in patients with EOUC. Conclusions In this population-based study from Korea, the pattern of medication use seemed comparable between the EOUC and N-EOUC groups. Moreover, patients with EOUC and those with N-EOUC have a similar disease course in terms of proximal disease extension, hospitaliza-tion, and colectomy.

Background/Aims: We aimed to evaluate the clinical characteristics and long-term prognosis of elderly-onset ulcerative colitis (EOUC) in Korean patients over a 30-year period using a wellestablished population-based cohort in the Songpa-Kangdong district of Seoul, Korea. Methods: Clinical characteristics and prognosis were compared between two groups: EOUC,defined as UC diagnosed in individuals aged ≥60 years and non-EOUC (N-EOUC), defined asUC diagnosed in individuals aged 18 to 59 years. Results: We identified 99 patients with EOUC (10.3%) and 866 patients with N-EOUC (89.7%) between 1986 and 2015. During the median follow-up of 104.5 months, the overall exposure tomedications was comparable between patients with EOUC and N-EOUC (p=0.091 for corticosteroids, p=0.794 for thiopurines, and p=0.095 for anti-tumor necrosis factor agents). The cumula-tive risks of disease outcomes were also comparable between patients with EOUC and N-EOUC (22.4% vs 30.4% for proximal disease extension [p=0.351], 11.9% vs 18.1% for hospitalization [p=0.240], and 2.3% vs 1.8% for colectomy [p=0.977]) at 10 years after diagnosis. Multivariate Cox regression analysis revealed that corticosteroid use at diagnosis was an independent predic-tor of proximal disease extension (hazard ratio [HR], 6.216; 95% confidence interval [CI], 1.314 to 28.826) and hospitalization (HR, 11.241; 95% CI, 3.027 to 41.742) in patients with EOUC. Conclusions In this population-based study from Korea, the pattern of medication use seemed comparable between the EOUC and N-EOUC groups. Moreover, patients with EOUC and those with N-EOUC have a similar disease course in terms of proximal disease extension, hospitaliza-tion, and colectomy.

Since a novel beta-coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in December 2019, there has been a rapid global spread of the virus. Genomic surveillance was conducted on samples isolated from infected individuals to monitor the spread of genetic variants of SARS-CoV-2 in Korea. The Korea Disease Control and Prevention Agency performed whole genome sequencing of SARS-CoV-2 in Korea for 1 year (January 2020 to January 2021). A total of 2,488 SARSCoV-2 cases were sequenced (including 648 cases from abroad). Initially, the prevalent clades of SARSCoV-2 were the S and V clades, however, by March 2020, GH clade was the most dominant. Only international travelers were identified as having G or GR clades, and since the first variant 501Y.V1 was identified (from a traveler from the United Kingdom on December 22 nd , 2020), a total of 27 variants of 501Y.V1, 501Y.V2, and 484K.V2 have been classified (as of January 25 th , 2021). The results in this study indicated that quarantining of travelers entering Korea successfully prevented dissemination of the SARS-CoV-2 variants in Korea.

BACKGROUND/AIMS: Delayed post-endoscopic submucosal dissection (ESD) bleeding (DPEB) is difficult to predict and there is controversy regarding the usefulness of prophylactic hemostasis during second-look endoscopy. This study evaluated the risk factors related to DPEB, the relationship between clinical outcomes and the Forrest classification, and the results of prophylactic hemostasis during second-look endoscopy. METHODS: Second-look endoscopy was performed on the day after ESD to check for recent hemorrhage or potential bleeding and the presence of artificial ulcers in all patients. RESULTS: DPEB occurred in 42 of 581 patients (7.2%). Multivariate analysis determined that a specimen size ≥40 mm (odds ratio [OR], 3.03; p=0.003), and a high-risk Forrest classification (Forrest Ib+IIa+IIb; OR, 6.88; p<0.001) were risk factors for DPEB. DPEB was significantly more likely in patients classified with Forrest Ib (OR, 24.35; p<0.001), IIa (OR, 12.91; p<0.001), or IIb (OR, 8.31; p<0.001) ulcers compared with Forrest III ulcers. There was no statistically significant difference between the prophylactic hemostasis and non-hemostasis groups (Forrest Ib, p=0.938; IIa, p=0.438; IIb, p=0.397; IIc, p=0.773) during second-look endoscopy. CONCLUSIONS: The Forrest classification of artificial gastric ulcers during second-look endoscopy seems to be a useful tool for predicting delayed bleeding. However, routine prophylactic hemostasis during second-look endoscopy seemed to not be useful for preventing DPEB.
Classification* ; Endoscopy* ; Hemorrhage ; Hemostasis ; Hemostasis, Endoscopic ; Humans ; Multivariate Analysis ; Risk Factors ; Stomach Neoplasms ; Stomach Ulcer ; Ulcer*

PURPOSE: The purpose of this study was to examine students' perception of the educational environment of medical schools in Korea. METHODS: A total of 9,096 of 12,035 students (75.6%) responded to our questionnaire. This study was conducted at the end of the 2013 academic year using the Dundee Ready Education Environment Measure (DREEM) at 40 medical schools in Korea. DREEM comprises five domains: students' perceptions of learning (SPL); students' perceptions of teachers (SPT); students' academic self-perceptions; students' perceptions of atmosphere; and students' social self-perception. The data were analyzed using descriptive statistics, independent t-test, and one-way analysis of variance. RESULTS: The overall mean DREEM score was 113.97 (of 200), and the scores for the 40 medical schools ranged from 100.24 to 134.32. The overall mean and domains scores of the DREEM differed significantly between educational systems, grades, genders, and academic achievement levels. Graduate-level medical students had higher scores for the DREEM and its five domains than undergraduate medical students. The scores were lowest in second-year students (mean, 111.80). Male students' perceptions were significantly higher than those of female students except for SPL and SPT. High academic achievers' perceptions were also greater versus low academic achievers. CONCLUSION: Students' perceptions of their educational environment are positive in Korea. The learning environment should be evaluated by curriculum planners and administrators of medical schools to improve its quality.
Achievement ; *Attitude ; *Education, Medical, Undergraduate ; Female ; Humans ; Male ; Perception ; Republic of Korea ; *Schools, Medical ; *Students, Medical ; Surveys and Questionnaires

OBJECTIVE: To determine the diagnostic cutoff values of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE). METHODS: Twenty-five elbows of 23 patients (9 females, 16 males) diagnosed with UNE and 30 elbows of 30 healthy controls (15 females, 15 males) were included in our study. The ulnar nerve cross-sectional area (CSA) was measured at the Guyon canal, midforearm, and maximal swelling point (MS) around the elbow (the cubital tunnel inlet in healthy controls). CSA measurements of the ulnar nerve at each point, the Guyon canal-to-MS ulnar nerve area ratio (MS/G), and the midforearm-to-MS ulnar nerve ratio (MS/F) were calculated. RESULTS: Among the variables, only CSA at MS, MS/G, and MS/F displayed significant differences between the control and patient groups. The cutoff value for diagnosing UNE was 8.95 mm2 for the CSA at MS (sensitivity 93.8%, specificity 88.3%), 1.99 for the MS/G (sensitivity 75.0%, specificity 73.3%), and 1.48 for the MS/F (sensitivity 93.8%, specificity 95.0%). CONCLUSION: These findings may be helpful to diagnose UNE.
Bays ; Elbow* ; Female ; Humans ; Ulnar Nerve ; Ulnar Neuropathies* ; Ultrasonography* ; United Nations

PURPOSE: The purpose of this study was to compare the perception of learning outcomes between faculty and students in medical schools. METHODS: A total of 1,766 medical students and 436 faculty members participated in the survey. They responded to the perception of four learning outcomes: medical knowledge and problem solving, clinical skills, medical ethics, and clinical communication. The participants responded to the education and achievement levels of the learning outcomes. RESULTS: In all four learning outcomes, the student's perception of education level differed by educational system, and the students in mixed systems had the highest scores. Students differed significantly in achievement level of medical ethics between genders, wherein male students perceived their achievement level to be higher than females. Students perceived their achievement level to be lower than the education level. The students' clinical skills were the highest in the education and achievement levels. The faculty perceived the education level to be higher than the student's achievement level. In particular, the faculty's perception of education level of medical knowledge and problem solving was the highest, whereas the students' achievement level of it was lower. The faculty assessed the education level to be higher than students. The students showed higher perception of achievement level than faculty. CONCLUSION: There were perceptual differences in learning outcomes between students and faculty. The results of this study are expected to be used to design outcome-based learning methods.
Clinical Competence ; Education* ; Ethics, Medical ; Female ; Humans ; Learning* ; Male ; Problem Solving ; Schools, Medical* ; Students, Medical