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A full colonoscopy is currently required in children and adolescents with colorectal polyps, because of their potential of neoplastic transformation and complications such as intussusception. We aimed to analyze the associations of polyp characteristics in children and adolescents with colorectal polyps. Based on these findings, we also aimed to reevaluate the necessity of conducting a full colonoscopy.Pediatric patients18 years of age who had undergone a colonoscopic polypectomy and those with5 colorectal polyps were included in this multicenter, retrospective study. Baseline clinicodemographics, colonoscopic and histologic findings were investigated.A total of 91 patients were included. Multivariate logistic regression analysis showed that polyp size was the only factor associated with the presence of any polyps located proximal to the splenic flexure (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.28 to 4.28; p=0.007). Furthermore, polyp location proximal to the splenic flexure and sessile morphology were associated with the presence of any adenomatous polyp (OR, 8.51; 95% CI, 1.43 to 68.65; p=0.023; OR, 18.41; 95% CI, 3.45 to 173.81; p=0.002, respectively).In children and adolescents presenting with5 colorectal polyps, polyp size and the presence of any adenomatous polyp were positively associated with polyp location proximal to the splenic flexure. This finding supports the necessity of a full colonoscopic exam in pediatric patients with colorectal polyps for the detection of polyps before the occurrence of complications such as intussusception or neoplastic transformation.

The optimal treatment goal in Crohn's disease (CD) is endoscopic healing (EH). However, transmural healing (TH) facilitated by the development and increasing performance of magnetic resonance enterography (MRE) is emerging as a potential treatment goal.To assess TH rates after 1 year of treatment by MRE and its relationship with EH in paediatric patients with CD receiving anti-tumour necrosis factor (TNF) agents, and to investigate factors associated with TH after 1 year of treatment.This multi-centre, prospective, observational study included Korean paediatric patients with luminal CD diagnosed at age19 years who were naïve to anti-TNF treatment. They simultaneously underwent ileocolonoscopy and MRE at baseline and after 1 year of treatment with biologics.We included 116 patients. At 1 year, EH and TH were achieved in 59.5% (69/116) and 38.8% (45/116) of the patients, respectively. Both EH and TH was observed in 35.3% (41/116), EH without TH in 24.1% (28/116), TH without EH in 3.4% (4/116), and neither EH nor TH in 37.1% (43/116). Moreover, 59.4% (41/69) of patients who achieved EH at 1 year exhibited TH, and 91.1% (41/45) of patients who achieved TH exhibited EH. Baseline MaRIA score was associated with TH according to a multivariate analysis (OR 0.97, 95% CI 0.95-0.99, p = 0.023).TH is a more stringent goal than EH. Regular follow-up evaluation of transmural status, and efforts to achieve TH, may alter the natural course of CD in the era of treat-to-target.

We investigated whether the severity of anxiety among children undergoing endoscopy could affect sedation. We prospectively recruited patients under 18 years of age who were scheduled to undergo esophagogastroduodenoscopy (EGD). Baseline anxiety was evaluated using the Spence Children’s Anxiety Scale (SCAS). Our analysis considered the type and dose of sedative drugs, degree of sedation, and complications associated with sedation according to the scale score. The mean total SCAS T-scores and each subscale score were significantly higher in the 6–12-year age group. The mean T-score among patients who exhibited irritability during EGD was higher than that among other patients, with significant differences in the Total, Obsessive Disorder, Panic Agoraphobia and General Anxiety subscales. The midazolam doses of children exhibiting irritability were more likely to need higher ( p = 0.006). Other sedation-related complications were not associated with the T-scores in each subscale. Total sleep time was not associated with any T-score subscales. Anxiety levels were significantly higher among 6–12-year-olds and children exhibiting irritability. Anxiety was often associated with irritability, difficulties achieving adequate sedation during EGD, and additional sedative drug administration. We recommend higher doses or more potent drugs to facilitate endoscopy for children with high anxiety levels.

Background Several groups have proposed models to predict disease outcomes in paediatric Crohn’s disease [CD], notably the RISK, GROWTH, and the Porto group, but none were externally validated. We aimed to explore these predictive models and individual predictors summarised by the PIBD-ahead project in a prospective inception cohort of paediatric CD. Methods We included children who were diagnosed with CD at two medical centres and followed them at 3 and 12 months thereafter as well as at the last follow-up. Outcomes included steroid-free remission [SFR], surgery, and stricturing/fistulising disease. Results In all 155 children were included (median follow-up of 31 [16–48] months, 107 [71%] had moderate-to-severe disease). Stricturing and penetrating disease at diagnosis were noted in 34 [22%] and two [1.3%] children, respectively, and these were excluded from the relevant analyses. At 1 year, 10 [8.3%] developed new stricturing disease, two [1.7%] developed penetrating disease, seven [5%] required intestinal surgery, and 15 [10%] required perianal surgery. The sensitivity/specificity/positive predictive value [PPV]/negative predictive value [NPV] of the GROWTH criteria for predicting SFR at 12 months [occurring in 70% of children] were 20%/85%/76%/31% and for surgery at 2 years were 96%/20%/16%/96%, respectively. Strictures were predicted by the RISK model with sensitivity/specificity/PPV/NPV of 33%/73%/18%/86%, respectively. The sensitivity/specificity/PPV/NPV of the Porto criteria to predict surgery were 86%/10%/4%/94%, respectively. None of the Pediatric Inflammatory Bowel Disease-ahead [PIBD-ahead] predictors were associated with surgery or stricturing disease. Conclusions None of the three main predictive models in paediatric CD achieved sufficient accuracy, far from that reported in the original cohorts. This highlights the necessity of external validation in any prediction model prior to its implementation in clinical practice

Perianal fistulizing diseases, namely perianal fistulas and/or abscesses, are well-known complications of Crohn's disease (CD). These are known to develop more frequently in Asian children with CD, especially in the early stages of the disease course. Approximately half of the pediatric CD cases in Korea present with perianal fistulizing diseases at diagnosis. We report a rare case of a 12-year-old boy with CD with an incidental discovery of a perianal abscess on pelvic magnetic resonance imaging during CD diagnosis. No symptoms or signs of perianal fistulizing disease were identified. The early diagnosis of the perianal abscess enabled timely and effective treatment. Considering the high incidence of concomitant perianal CD in Korean children at diagnosis, perianal imaging may be useful and should be considered during diagnostic evaluation, even in patients with no subjective or objective findings indicating perianal CD.

Background/Aims Anti-drug antibodies (ADAs) can develop during treatment with anti-tumor necrosis factor (TNF) agents. We aimed to investigate the factors associated with immunogenicity of anti-TNF agents in pediatric patients with inflammatory bowel disease (IBD) and observe the clinical course of ADA-positive patients. Methods Pediatric IBD patients receiving maintenance treatment with anti-TNF agents who had been tested for ADAs against infliximab (IFX) or adalimumab (ADL) were included in this cross-sectional study. Factors associated with ADA positivity were investigated by analyzing clinicodemographic, laboratory, and treatment-related factors. Results A total of 76 patients (Crohn’s disease, 65; ulcerative colitis, 11) were included. Among these, 59 and 17 patients were receiving IFX and ADL, respectively. ADAs were found in 10 patients (13.2%), all of whom were receiving IFX. According to multivariable logistic regression analysis, the IFX trough level (TL) was associated with ADA positivity (odds ratio, 0.25; 95% confidence interval [CI], 0.08 to 0.51; p=0.002). According to the receiver operating characteristic analysis, the optimal cutoff of the IFX TLs for stratifying patients based on the presence of ADAs against IFX was 1.88 μg/mL (area under curve, 0.941; 95% CI, 0.873 to 1.000; sensitivity, 80.0%; specificity, 95.9%; p

Various methods have been implemented for pediatric gastrostomy tube placement. We aimed to investigate the performance status of pediatric gastrostomy in South Korea and to present indications and appropriate methods for domestic situations.A survey was conducted among pediatric endoscopists who performed upper gastrointestinal endoscopy in Korea. The questionnaire consisted of 16 questions on gastrostomy performance status.Among the 48 institutions where the survey was applied, 36 (75%) responded. Of the 36 institutions, gastrostomy was performed in 31 (86.1%). The departments in which gastrostomy was performed were pediatrics at 26 institutions (81.3%), surgery at 24 institutions (75.0%), internal medicine at 9 institutions (28.1%), and radiology at 7 institutions (21.9%). There were 18 institutions (66.7%) using the pull method for percutaneous endoscopic gastrostomy (PEG) and nine institutions (33.3%) using the push method. When performing gastrostomies, fundoplication procedures were performed in 19 institutions (61.3%), if deemed necessary. However, 12 institutions (38.7%) answered that gastrostomy was always implemented alone. Complications after gastrostomy included buried bumper syndrome, wound infection, leakage, tube migration, and incorrect opening site in the stomach, but the number of cases with complications was very small.In Korea, a pediatric gastrostomy is implemented in various ways depending on the institution. Clinicians are concerned about choosing the most effective methods with fewer complications after the procedure. In our study, we reported only a few complications. Korea has good accessibility for pediatric gastrointestinal endoscopy, and this survey showed that it is a safe procedure that can be considered initially in pediatric gastrostomy. This study is expected to help to create optimal pediatric PEG guidelines in Korea.

Juvenile polyposis/hereditary hemorrhagic telangiectasia (JPS/HHT) syndrome is a rare, autosomal dominant disorder caused by mutations in the SMAD4 gene, presenting with features of both juvenile polyposis syndrome (JPS) and HHT. Reports and studies of JPS/HHT syndrome are mostly from Western countries, while there are scarce reports from East Asian countries. We report a case of a Korean boy who had been previously diagnosed with JPS at 7 years and had first visited to our center at 15 years of age. Genetic studies of the patient and parents revealed a novel variant in the SMAD4 gene, SMAD4 c.1146_1163del; p.His382_Val387del (NM_005359.5), which had developed de novo. Numerous pedunculated and sessile polyps were observed throughout the gastrointestinal (GI) tract. Mucocutaneous telangiectases were observed on the lips, tongue, and jejunum, and arteriovenous malformations (AVMs) were observed in both lungs. This is the first case report of JPS/HHT syndrome in Korea, with a novel deletion variant in the SMAD4 gene. Patients with JPS should undergo genetic evaluation of associated genes including SMAD4, and those with genetically confirmed SMAD4 variants should undergo further evaluation for coexisting asymptomatic AVMs in order to prevent life-threatening complications of thrombotic emboli and pulmonary hemorrhage.

Objective This study aimed to determine the factors that affect successful esophageal foreign body (FB) removal using a Foley catheter and to identify methods to increase the success rate. Methods In this retrospective, cross-sectional study, we included pediatric patients who presented with esophageal FB impaction that was removed using a Foley catheter in the emergency departments of tertiary care and academic hospitals. We analyzed the effect of the patients' age, sex, and symptoms; FB type, size, and location; Foley catheter size; complications during FB removal; duration between FB ingestion and removal; operator's years of training; sedation; success rate of FB removal; endoscopy; and patient's posture during FB removal on the success of Foley catheter-based FB removal. Results Of the 43 patients we enrolled, Foley catheter-based FB removal was successful in 81.4% (35/43) but failed in 18.6% (8/43) of patients; no FB-removal-related complications were reported. There was no significant association between the success rate of Foley catheter-based FB removal and any study variable. A higher number of years in training tended to increase the success rate of Foley catheter-based FB removal, although statistical significance was not achieved. Conclusion Children's esophageal FB removal is a practical challenge in the emergency rooms, and using a Foley catheter is associated with a high success rate of the removal and low occurrence of complications. In this study, no single variable was found correlated with the success rate of Foley catheter-based esophageal FB removal in pediatric patients, which may indicate multiple variables interacting with one another to affect the success rate.

Vedolizumab (VDZ) has been approved for the treatment of inflammatory bowel diseases (IBDs) in patients aged ≥18 years. We report a case of a pediatric patient with Crohn disease (CD) who was successfully treated with VDZ. A 16-year-old female developed severe active pulmonary tuberculosis (TB) during treatment with infliximab (IFX). IFX was stopped, and TB treatment was started. After a 6-month regimen of standard TB medication, her pulmonary TB was cured; however, gastrointestinal symptoms developed. Due to the concern of the patient and parents regarding TB reactivation on restarting treatment with IFX, VDZ was started off-label. After the second dose of VDZ, the patient was in clinical remission and her remission was continuously sustained. Ileocolonoscopy at 1-year after VDZ initiation revealed endoscopic healing. Therapeutic drug monitoring conducted during VDZ treatment showed negative antibodies to VDZ. No serious adverse events occurred during the VDZ treatment. This is the first case report in Korea demonstrating the safe and effective use of VDZ treatment in a pediatric CD patient. In cases that require recommencement of treatment with biologics after recovery of active pulmonary TB caused by anti-tumor necrosis factor agents, VDZ may be a good option even in pediatric IBD.

BACKGROUND/OBJECTIVES To evaluate the nutritional status and prevalence of malnutrition in hospitalized children at admission and during hospitalization in South Korea. SUBJECTS/METHODS This first cross-sectional nationwide "Pediatric Nutrition Day (pNday)" survey was conducted among 872 hospitalized children (504 boys, 368 girls; 686 medical, 186 surgical) from 23 hospitals in South Korea. Malnutrition risk was screened using the Pediatric Yorkhill Malnutrition Score (PYMS) and the Screening Tool Risk on Nutritional status and Growth. Nutritional status was assessed by z-scores of weight-for-age for underweight, weight-for-height for wasting, and height-for-age for stunting as well as laboratory tests. RESULTS At admission, of the 872 hospitalized children, 17.2% were underweight, and the prevalence of wasting and stunting was 20.2% and 17.3%, respectively. During hospitalization till pNday, 10.8% and 19.6% experienced weight loss and decreased oral intake, respectively. During the aforementioned period, fasting was more prevalent in surgical patients (7.5%) than in medical patients (1.6%) (P < 0.001). According to the PYMS, 34.3% and 30% of the children at admission and on pNday, respectively, had a high-risk of malnutrition, requiring consultation with the nutritional support team (NST). However, only 4% were actually referred to the NST during hospitalization. CONCLUSIONS Malnutrition was prevalent at admission and during hospitalization in pediatric patients, with many children experiencing weight loss and poor oral intake. To improve the nutritional status of hospitalized children, it is important to screen and identify all children at risk of malnutrition and refer malnourished patients to the multidisciplinary NST for proper nutritional interventions.

Vedolizumab (VDZ) is currently licensed for use in adults for the treatment of inflammatory bowel disease (IBD). We aimed to investigate the clinical course of pediatric-onset IBD following treatment with VDZ as more than a secondary biologic agent. We also evaluated factors associated with secondary loss of response (LOR) and durability of VDZ treatment.Pediatric-onset IBD patients diagnosed at an age younger than 18 years who had received VDZ as more than a secondary biologic agent were included in this retrospective observational study conducted at the Department of Pediatrics of two centers in Korea. Comparative analysis was conducted between groups divided according to the development of secondary LOR during VDZ treatment.A total of 24 patients comprising 10 patients with Crohn's disease and 14 with ulcerative colitis were included. Of these, 19 were male and 5 were female. The mean age at diagnosis was 14.6 ± 2.5 years. The mean age at initiation of VDZ was 20.5 ± 2.8 years. Nine patients (37.5%) had received two or more biologic agents before starting VDZ. During a median of 0.9 years follow-up from VDZ initiation, 9 patients (37.5%) experienced LOR requiring interval shortening and 4 patients (16.7%) were changed to a different biologic agent. According to multivariate Cox proportional hazard regression analysis, administration of two or more biologic agents before VDZ treatment was the only factor positively associated with LOR (hazard ratio [HR], 5.6; 95% confidence interval [CI], 1.026-30.56;VDZ is safe and efficacious for the treatment of pediatric-onset IBD patients failing a primary biologic agent. The durability of VDZ may be enhanced by introducing VDZ earlier in the disease course. Further prospective studies in children are required in the future to validate these findings.

Studies on how the coronavirus pandemic has affected pediatric inflammatory bowel disease (PIBD) are lacking. We aimed to investigate the trends in epidemiology, characteristics, initial management, and short-term outcomes of PIBD in South Korea over the recent three years including the era of coronavirus disease 2019 (COVID-19).This multicenter study retrospectively investigated temporal trends in the epidemiology of PIBD in Korea. Annual occurrences, disease phenotypes, and initial management at diagnosis were analyzed from January 2018 to June 2021.A total of 486 patients from 17 institutions were included in this epidemiological evaluation. Analysis of the occurrence trend confirmed a significant increase in PIBD, regardless of the COVID-19 pandemic. In Crohn's disease, patients with post-coronavirus outbreaks had significantly higher fecal calprotectin levels than those with previous onset (1,339.4 ± 717.04 vs. 1,595.5 ± 703.94,Regardless of the COVID-19 pandemic, the number of patients with PIBD is increasing significantly annually in Korea. The initial management trends for PIBD have also changed. More research is needed to establish appropriate treatment guidelines considering the epidemiological and clinical characteristics of Korean PIBD.

Colorectal polyps are the most common cause of isolated hematochezia in children, which requires a colonoscopy for diagnosis. We aimed to investigate the potential utility of fecal calprotectin (FC) in assessing colorectal polyps detected by colonoscopy among children presenting with isolated hematochezia.Pediatric patients of the age of18 years who had undergone both colonoscopy and FC tests for isolated hematochezia from June 2016 to May 2020 were included in the present multicenter, retrospective, cross-sectional study. Comparative analysis was conducted between major causes of isolated hematochezia and FC cut-offs for discriminating colorectal polyps were explored.A total 127 patients were included. Thirty-five patients (27.6%) had colorectal polyps, followed by anal fissure (14.2%), ulcerative colitis (UC; 12.6%), and others. A significant difference in FC levels was observed between patients with colorectal polyps (median, 278.7 mg/kg), anal fissures (median, 42.2 mg/kg), and UC (median, 981 mg/kg) (FC may assist in assessing the cause of lower gastrointestinal tract bleeding in children who present with isolated hematochezia.

Translational medical research on hepatitis B virus (HBV) infection and chronic hepatitis B (CHB) pathogenesis provides guidance on strengthening the treatment and prevention strategies of CHB. Preventing vertical transmission is the key to eliminating HBV infection in children. The understanding of HBV replication, hepatocyte turnover, and the fate of covalently closed circular DNA (cccDNA) would help establish a personalized application of the guidelines, especially concerning the discontinuation of nucleos(t)ide analog (NA) treatment in children. Transplacental leakage of HBV-infected maternal blood is suggested as the leading cause of vertical transmission. Prenatal maternal prophylaxis could diminish maternal HBV viremia at delivery, to reduce the risk of neonatal HBV infection. The meaning of the expression “no additional risk of breast milk feeding” is thereby explained. Understanding the untreated natural course of CHB in children and the course changeable by treatment is important to apply individualistic strategies and avoid the immoral selection of treatment indications. NAs with potent efficacy and a high barrier to drug resistance should be used as first-line treatment to reduce the likelihood of NA-resistant HBV development because the rate of mutant HBV emergence might count on the infected hepatocyte turnover rate in chronic HBV infection. Although elimination of intranuclear cccDNA is difficult by NAs alone, a cure is possible by human immunity and hepatocyte turnover. The reduction of intranuclear cccDNA occurs after the destruction of HBV-infected hepatocytes, non-cytolytic immune response, apoptosis of hepatocytes, and compensatory cell proliferation. Therefore, consolidation therapy after NA-induced hepatitis B e-antigen seroconversion must be necessary for a sufficient period. This review also summarizes the treatment strategies of CHB in children based on the practical application of translational research.

Introduction: Autoimmune pancreatitis (AIP) is a rare extraintestinal manifestation of inflammatory bowel disease (IBD) which is typically responsive to corticosteroid treatment.Case Presentation: We report a case of a 17-year-old male diagnosed with ulcerative colitis who subsequently developed acute pancreatitis. Blood tests demonstrated elevated pancreatic enzyme levels of amylase (1319 U/L) and lipase (809 U/L). Abdominal computed tomography revealed peripancreatic fat stranding and the presence of a perisplenic pseudocyst. Azathioprine and mesalazine were stopped as possible causes of drug-induced pancreatitis. However, pancreatic enzymes remained elevated and corticosteroid treatment was started. Despite corticosteroid therapy, amylase and lipase levels continued to increase. Infliximab was started due to a flare in gastrointestinal symptoms of ulcerative colitis. Follow-up abdominal ultrasonography revealed a pancreatic tail mass. Tumor markers, including CA 19-9, were elevated and atypical cells were seen on histological examination of an endoscopic ultrasonography-guided fine needle aspiration biopsy. Surgical pancreaticosplenectomy was performed for suspected pancreatic neoplasm. Surprisingly, histology revealed chronic pancreatitis with storiform fibrosis and infiltration of IgG4-positive cells, compatible with AIP type 1. Thereafter, pancreatic enzymes gradually decreased to normal levels and the patient has been in remission for 9 months on infliximab monotherapy.Conclusion: Pediatric gastroenterologists should keep in mind that AIP may develop during the natural course of pediatric IBD. Moreover, the development of pancreatic fibrosis may be non-responsive to corticosteroid treatment and mimic pancreatic neoplasia.

Collagenous gastritis (CG) is a rare disease diagnosed histologically by the subepithelial deposition of collagen bands thicker than 10 µm and the infiltration of inflammatory mononuclear cells in the lamina propria. The definite pathophysiology is yet to be elucidated. However, recent studies have suggested that the collagen deposition may be the result of a reparative process in response to an earlier inflammatory, autoimmune, infectious, or toxic insult. CG is divided into the pediatric- and adult-type. While the pediatric-type is limited to the stomach, the adult-type involves not only the stomach but also the intestine and/or colon. We report a rare case of adult-type CG in a 15-year-old boy who initially presented with abdominal pain and iron-deficiency anemia. Esophagogastroduodenoscopy (EGD) revealed findings suspicious for Helicobacter pylori (H. pylori) gastritis. Although histology did not reveal the organism, campylobacter-like organism (CLO) test was positive. Based on the diagnosis of suspicious H. pylori gastritis, eradication was conducted using the triple drug regimen. However, symptoms of intermittent abdominal pain persisted and diarrhea newly developed one year later. Histologic results from biopsies from the stomach, duodenum, and colon revealed findings compatible with CG, collagenous duodenitis (CD), and collagenous colitis (CC). This is the first pediatric case of collagenous gastroduodenocolitis (CGDC) reported in Asia. It is no longer assumed that adult-type and pediatric-type CG should be classified as an independent disease, but should be considered as similar diseases on a continuous spectrum. Therefore, children and adolescents diagnosed with CG should also consider undergoing a colonoscopy for the evaluation of possible coexisting CC when concurrent lower gastrointestinal symptoms are present. Moreover, considering the possibility of negative findings on the first endoscopy, repeat endoscopy should be considered when symptoms persist.

The prevalence of cystic fibrosis (CF) is considerably lower in Asian populations compared with that of Caucasians. Cases of CF are typically due to mutations in the CF transmembrane conductance regulator gene with autosomal recessive inheritance. Here, we report two cases of newly diagnosed CF in Korea—a 13-year-old boy and his 5-year-old brother. The older brother was admitted to our hospital for evaluation and treatment of recurrent abdominal pain, frequent diarrhea, and failure to thrive. Fecal calprotectin (FC) was elevated, and when combining this with his clinical presentation, inflammatory bowel disease (IBD) or eosinophilic gastroenteritis (EoGE) was the first impression of his disease. Several ulcerative lesions were observed on ileocolonoscopy. However, incidental findings of suspicious bronchiectatic lesions were observed on plain radiography, which were confirmed by chest computed tomography. Moreover, diffuse bowel wall thickening with pancreatic atrophy was also incidentally detected by computed tomography of the abdomen. Comprehensively, these findings were highly suggestive of CF. Therefore, diagnostic exome sequencing was conducted, which revealed compound heterozygous variants of c.263T>G (p.Leu88*) and c.2977G>T (p.Asp993Tyr) in the CF transmembrane conductance regulator gene. Although symptoms in the younger brother were not as prominent as the older brother, genetic test was also conducted, which revealed the same mutation. We report the identification of a novel variant, p.Asp993Tyr, in siblings with Korean heritage. Although CF is rare in Koreans, it should be included in the differential diagnosis of IBD.

NUDT15 polymorphisms are associated with leukopenia during treatment with thiopurines. However, data regarding its effect on treatment outcomes are scarce.To investigate the outcomes between NUDT15 normal and intermediate metabolisers in paediatric patients with Crohn's disease (CD) treated with a combination therapy of infliximab (IFX) and azathioprine (AZA).In this retrospective observational study, 143 patients categorised into the NUDT15 normal and intermediate metaboliser groups were compared based on clinical remission (CR), biochemical remission (BR), mucosal healing (MH) at 1 year treatment, IFX trough levels (TLs), antibodies to IFX (ATIs), 6-thioguanine nucleotide (6-TGN) levels, loss of response (LOR) and IFX durability.No significant differences were observed between the groups in CR, BR, MH at 1 year, whereas IFX TLs and ATIs and 6-TGN levels were comparable. However, LOR (6.5% vs 27.7%, P = 0.025) was significantly lower and IFX durability significantly higher (96.8% vs 80.4% P = 0.027) in the intermediate group. Multivariable Cox proportional hazard regression analysis showed that ATI positivity (hazard ratio (HR): 4.76, 95% CI: 2.25-10.07, P 0.001) and the NUDT15 metaboliser group was associated with LOR (HR: 0.18, 95% CI: 0.04-0.76, P = 0.019). The Kaplan-Meier survival curves showed that the LOR-free survival rate was significantly lower in normal metabolisers (log-rank test P = 0.009).NUDT15 intermediate metabolisers were associated with lower LOR in paediatric patients with CD treated with IFX and AZA combination therapy. This finding may partially explain the longer durability of IFX in Korean children than their counterparts in Western countries.

We aimed to compare the differences in pediatric Crohn's disease (CD) and ulcerative colitis (UC) at diagnosis in Korea.This was a multicenter, registry-based, inception cohort study conducted at five centers in Korea between 2013 and 2017. Baseline demographics, clinical characteristics, and results from laboratory, endoscopic, radiologic examinations were compared between pediatric CD and UC patients who were19 years old at diagnosis.A total 307 patients were included (227 CD [73.9%] and 80 UC [26.1%]). The male to female ratio was 2.49:1 for CD, and 1.49:1 for UC (p=0.019). Median age at diagnosis was 14.4 years (interquartile range, 12.4 to 16.2) for CD, and 14.4 years (interquartile range, 11.7 to 16.5) for UC (p=0.962). Hematochezia was the only dominant symptom in UC patients compared to CD patients (86.2% vs 30.8%, p0.001). White blood cell counts, platelet counts, erythrocyte sedimentation rate, and C-reactive protein levels were significantly higher, and serum albumin level was significantly lower in CD patients than in UC patient. Anti-This is the first a multicenter study in Korea to compare the differences between pediatric CD and UC at diagnosis in Korea. A large-scale, national study is expected to better clarify these findings in the future.

BACKGROUND: The occurrences of infection-related systematic diseases, such as Henoch-Schönlein Purpura (HSP), intussusception, and mucocutaneous lymph node syndrome (MCLS) may have decreased, similarly to the decreased occurrence of infectious diseases following the Coronavirus disease 2019 (COVID-19) pandemic. We aimed to investigate whether there was a change in the occurrence of these diseases in South Korea after the spread of the COVID-19 pandemic. METHODS: In this multicenter, retrospective study conducted in 16 medical centers in South Korea patients diagnosed with HSP, intussusception, and MCLS at the age of

Background It is uncertain whether non-alcoholic fatty liver disease (NAFLD) is associated with subclinical hypothyroidism (SH) in pediatric patients. The purpose of this study was to investigated the prevalence and related factors of SH in pediatric patients with NAFLD. We also evaluate the association between liver fibrosis and SH. Methods We retrospectively reviewed medical records for patients aged 4 to 18 years who were diagnosed with NAFLD and tested for thyroid function from January 2015 to December 2019 at 10 hospitals in Korea. Results The study included 428 patients with NAFLD. The prevalence of SH in pediatric NAFLD patients was 13.6%. In multivariate logistic regression, higher levels of steatosis on ultrasound and higher aspartate aminotransferase to platelet count ratio index (APRI) score were associated with increased risk of SH. Using receiver operating characteristic curves, the optimal cutoff value of the APRI score for predicting SH was 0.6012 (area under the curve, 0.67; P < 0.001; sensitivity 72.4%, specificity 61.9%, positive predictive value 23%, and negative predictive value 93.5%). Conclusion SH was often observed in patients with NAFLD, more frequently in patients with more severe liver damage. Thyroid function tests should be performed on pediatric NAFLD patients, especially those with higher grades of liver steatosis and fibrosis., Graphical Abstract