Gut Microbial Signatures in Pediatric Crohn's Disease Vary According to Disease Activity Measures and Are Influenced by Proxies of Gastrointestinal Transit Time: An ImageKids Study.

INTRODUCTION: We investigated relationships between disease activity measures and the gut microbiome in children with Crohn's disease (CD) and how these were confounded by gastrointestinal transit time. METHODS: Microbiome was profiled (16S rRNA sequencing) in feces from 196 children with CD. Sixty participants also provided samples after 18 months. Mural inflammation (Pediatric Inflammatory Crohn's Magnetic Resonance Enterography Index, PICMI), the simple endoscopic score for CD, and the weighted pediatric Crohn's disease activity index (wPCDAI) were assessed. Fecal calprotectin, plasma C-reactive protein (CRP), and fecal water content (FWC), a proxy of gastrointestinal transit time, were measured too. RESULTS: Microbiome α diversity, clustering, and differential taxa were related to disease status, but varied remarkably by disease activity measure used. The strongest relationships between microbiome and disease activity status were observed using wPCDAI; fewer or no relationships were seen using more objective measures like PICMI. Taxa predictive of disease activity status were dependent on the disease activity measure used with negligible overlap. Active disease was associated with more pathobionts (eg, Viellonella, Enterobacterales) and fewer fiber-fermenting organisms. The effect FWC had on microbiome superseded the effect of active disease for all disease activity measures, particularly with wPCDAI. Accounting for FWC, the differences in microbial signatures explained by disease activity status were attenuated or lost. CONCLUSIONS: In CD, microbiome signatures fluctuate depending on the measure used to assess disease severity; several of these signals might be secondary disease effects linked with changes in gut motility in active disease. PICMI appears to be less influenced when studying relationships between microbiome and mural inflammation in CD.

Microbiome signatures are related to Crohn's disease status but vary remarkably by disease activity measure used. The effect gut transit time has on microbiome supersedes and confounds the effect of active disease, particularly with the use of less objective disease activity measures.

Healthy First-Degree Relatives From Multiplex Families vs Simplex Families Have a Higher Subclinical Intestinal Inflammation, a Distinct Fecal Microbial Signature, and Harbor a Higher Risk of Developing Crohn's Disease.

BACKGROUND & AIMS: Unaffected first-degree relatives (FDRs) from families with ≥2 affected FDRs with Crohn's disease (CD, multiplex families) have a high risk of developing CD, although the underlying mechanisms driving this risk are poorly understood. We aimed to identify differences in biomarkers between FDRs from multiplex vs simplex families and investigate the risk of future CD onset accounting for potential confounders. METHODS: We assessed the Crohn's and Colitis Canada Genetic Environmental Microbial cohort of healthy FDRs of patients with CD. Genome-wide CD-polygenic risk scores, urinary fractional excretion of lactulose-to-mannitol ratio, fecal calprotectin (FCP), and fecal 16S ribosomal RNA microbiome were measured at recruitment. Associations between CD multiplex status and baseline biomarkers were determined using generalized estimating equations models. Cox models were used to assess the risk of future CD onset. RESULTS: There were 4051 participants from simplex families and 334 from CD multiplex families. CD multiplex status was significantly associated with higher baseline FCP (P = .026) but not with baseline CD-polygenic risk scores or the lactulose-to-mannitol ratio. Three bacterial genera were found to be differentially abundant between both groups. CD multiplex status at recruitment was independently associated with an increased risk of developing CD (adjusted hazard ratio, 3.65; 95% confidence interval, 2.18-6.11, P < .001). CONCLUSION: Within FDRs of patients with CD, participants from multiplex families had a 3-fold increased risk of CD onset, a higher FCP, and an altered bacterial composition, but not genetic burden or altered gut permeability. These results suggest that putative environmental factors might be enriched in FDRs from multiplex families.

Body Surface Area-Based Dosing of Infliximab is Superior to Standard Weight-Based Dosing in Children With Very Early Onset Inflammatory Bowel Disease.

Background and Aims: Children with very early onset inflammatory bowel disease (VEO-IBD) are uniquely at risk of inadequate infliximab (IFX) exposure. We studied the association between standard body weight (BW)-based and body surface area (BSA)-based dosing strategies and outcomes. Methods: We identified VEO-IBD patients treated with IFX before 9 years at a single center. Patients were separated into those that received a BSA-based dose (200 mg/m2) and standard BW dosing (5 mg/kg). IFX drug levels, dose intensification, time on steroids, and long-term outcomes were compared. Receiver operator characteristic curves determined the optimal BW- and BSA-based dose to achieve a trough ≥10 µg/ml at dose 4 (IFX#4). Results: Forty-three children with VEO-IBD were identified. Receiver operator characteristic curves demonstrated optimal BW- and BSA-based doses to achieve IFX trough ≥10 µg/ml at IFX#4 were 7.5 mg/kg and 180mg/m2. Children were classified to standard BW dosing (22/43) and BSA dosing (10/43). IFX#4 trough was significantly higher in those who received BSA dosing (BSA 18.6 µg/ml [interquartile range 10.8-28.1] vs BW 5.1 µg/ml [interquartile range 2.6-10.7], P = .04). BSA dosing was more likely to achieve a target drug level >10 µg/ml at IFX#4 (BSA 70% vs BW 18%, P = .02). BW dosing was associated with a greater likelihood of dose escalation (BW 82% vs BSA 30%, P < .01) and a shorter time to first escalation. BSA dosing was associated with shorter time spent on steroids (P = .02). Conclusion: Young children require higher IFX dosing to achieve adequate drug exposure. Our data support the use of a BSA-based dose of 200 mg/m2 or, if a BW-based approach is used, 7.5 mg/kg. BSA dosing allows the use of a consistent dose over the age and weight spectrum.

High Healthcare Costs in Childhood Inflammatory Bowel Disease: Development of a Prediction Model Using Linked Clinical and Health Administrative Data.

BACKGROUND: The incidence of pediatric-onset inflammatory bowel disease (IBD) and the costs of caring for individuals with IBD are both increasing. We calculated the direct healthcare costs of pediatric IBD in the first year after diagnosis and developed a model to predict children who would have high costs (top 25th percentile). METHODS: Using data from the Canadian Children IBD Network inception cohort (≤16 years of age, diagnosed between 2013 and 2019) deterministically linked to health administrative data from Ontario, Canada, we estimated direct healthcare and medication costs accrued between 31 and 365 days after diagnosis. Candidate predictors included age at diagnosis, sex, rural/urban residence location, distance to pediatric center, neighborhood income quintile, IBD type, initial therapy, disease activity, diagnostic delay, health services utilization or surgery around diagnosis, regular primary care provider, and receipt of mental health care. Logistic regression with stepwise elimination was used for model building; 5-fold nested cross-validation optimized and improved model accuracy while limiting overfitting. RESULTS: The mean cost among 487 children with IBD was CA$15 168 ± 15 305. Initial treatment (anti-tumor necrosis factor therapy, aminosalicylates, or systemic steroids), having a mental health care encounter, undergoing surgery, emergency department visit at diagnosis, sex, and age were predictors of increased costs, while having a regular primary care provider was a predictor of decreased costs. The C-statistic for our model was 0.71. CONCLUSIONS: The cost of caring for children with IBD in the first year after diagnosis is immense and can be predicted based on characteristics at diagnosis. Efforts that mitigate rising costs without compromising quality of care are needed.

Cost of caring for children with IBD is high­CA$15 168 between 31 and 365 days from diagnosis in 487 Canadian children. Predictors of high costs included anti-tumor necrosis factor therapy and mental health care, with lower costs in those with a primary-care provider.

Serum Metabolites Relate to Mucosal and Transmural Inflammation in Pediatric Crohn Disease.

BACKGROUND AND AIMS: We aimed to identify serum metabolites associated with mucosal and transmural inflammation in pediatric Crohn disease (pCD). METHODS: Fifty-six pCD patients were included through a pre-planned sub-study of the multicenter, prospective, ImageKids cohort, designed to develop the Pediatric Inflammatory Crohn's MRE Index (PICMI). Children were included throughout their disease course when undergoing ileocolonoscopy and magnetic resonance enterography (MRE) and followed for 18 months when MRE was repeated. Serum metabolites were identified using liquid chromatography/mass spectroscopy. Outcomes included: PICMI, the simple endoscopic score (SES), faecal calprotectin (FCP), and C-reactive protein (CRP), to assess transmural, mucosal, and systemic inflammation, respectively. Random forest models were built by outcome. Maximum relevance minimum redundancy (mRMR) feature selection with a j-fold cross validation scheme identified the best subset of features and hyperparameter settings. RESULTS: Tryptophan and glutarylcarnitine were the top common mRMR metabolites linked to pCD inflammation. Random forest models established that amino acids and amines were among the most influential metabolites for predicting transmural and mucosal inflammation. Predictive models performed well, each with an area under the curve (AUC) > 70%. In addition, serum metabolites linked with pCD inflammation mainly related to perturbations in citrate cycle (TCA cycle), aminoacyl-tRNA biosynthesis, tryptophan metabolism, butanoate metabolism, and tyrosine metabolism. CONCLUSIONS: We extend on recent studies, observing differences in serum metabolite between healthy controls and Crohn disease patients, and suggest various associations of serum metabolites with transmural and mucosal inflammation. These metabolites could improve the understanding of pCD pathogenesis and assess disease severity.

Recommendations for Broadening Eligibility Criteria in Inflammatory Bowel Disease Clinical Trials.

BACKGROUND: Clinical trial recruitment for patients with inflammatory bowel disease (IBD) has become more challenging over time. We aimed to develop recommendations for broadening IBD clinical trial eligibility to improve the inclusion of a more representative patient population in a more efficient timeline. METHODS: We applied the RAND/UCLA Appropriateness Method focused on broadening IBD clinical trial eligibility. A literature review was performed for 7 domains, each representing a different area related to trial recruitment. Based on these domains, 32 statements were developed. A questionnaire was sent to IBD specialists to anonymously vote on each statement with regards to its appropriateness and feasibility. After the first round of voting, participants met for a moderated discussion to review all statements. At the end of the discussion a second round of anonymous voting led to the final recommendations. RESULTS: The final round of voting resulted in 26 statements. All were rated as feasible and 25 of 26 rated as appropriate. Recommendations generally are to be more inclusive of complicated disease phenotypes, more liberal around safety criteria, to recognize the importance of non-invasive imaging and biomarkers, to minimize the washout period and to not enforce a minimum or maximum number of prior medications, to allow a recently recorded colonoscopy to count as a baseline study, and to be less restrictive of age. CONCLUSION: Recommendations to broaden clinical trial eligibility were found to be both appropriate and feasible with a high degree of agreement amongst an international group of IBD specialists.

Ustekinumab in paediatric patients with moderately to severely active Crohn's disease: UniStar study long-term extension results.

OBJECTIVES: To assess the efficacy, safety, immunogenicity, and pharmacokinetics through 240 weeks of ustekinumab treatment in paediatric patients from the long-term extension (LTE) of the phase 1, double-blind UniStar trial. METHODS: Paediatric patients with moderately to severely active Crohn's disease (CD) were randomised 1:1 and stratified by body weight (<40 or ≥40 kg) to low- or high-dose intravenous ustekinumab followed by a subcutaneous maintenance dose at Week 8. At Week 16, patients were eligible to enter the LTE at the discretion of the investigator and continued maintenance dosing every 8 weeks up to Week 240. RESULTS: Of the 34 patients who entered the LTE, 25 patients with evaluable data completed Week 48, and 41.2% (14/34) achieved clinical remission at Week 48. Among the 24 patients with Week-0 C-reactive protein (CRP) levels ≥3 mg/L, 29.2% (7/24) achieved normalisation of CRP at Week 48, while imputing missing data as failures. Through Week 240, the most common adverse events were infections (n = 28) and gastrointestinal disorders (n = 26). The most common serious adverse event was worsening of CD (n = 6). Only one patient had detectable antibodies to ustekinumab. Median serum ustekinumab concentrations remained consistent through Week 48, were detectable through Week 224, and trended lower in patients <40 kg. CONCLUSIONS: Efficacy and pharmacokinetics through 1 year and safety and immunogenicity through 4 years of ustekinumab treatment in paediatric patients with CD were generally comparable to those previously reported in adults.

Mental Health Experiences of Adolescents and Young Adults with Inflammatory Bowel Disease During Transition to Adult Care: A Qualitative Descriptive Study.

OBJECTIVE: To explore the mental health experiences of adolescents and young adults (AYA) with inflammatory bowel disease (IBD) enrolled in a randomized controlled trial evaluating the impact of a multimodal transition intervention. STUDY DESIGN: Virtual semistructured interviews were held with 21 AYA aged 16 through 18 years with IBD. Guided by qualitative description, interviews were digitally recorded, transcribed verbatim, and analyzed using an inductive approach to reflexive thematic analysis. RESULTS: Three themes were generated from the data: (1) a continuum of integration between IBD and personal identity in adolescence and young adulthood; (2) manifestations of the mind-gut connection among AYA with IBD; and (3) hopes and priorities for addressing mental health in IBD care. CONCLUSIONS: AYA with IBD endorsed the criticality of incorporating mental health discussions into routine care during the transition to adult care, given the co-occurrence of psychosocial stressors throughout this period. A series of factors promoting and hindering the integration of IBD into one's identity were identified and could be explored in clinical encounters.

Environmental Factors Associated With Risk of Crohn's Disease Development in the Crohn's and Colitis Canada - Genetic, Environmental, Microbial Project.

BACKGROUND & AIMS: To date, it is unclear how environmental factors influence Crohn's disease (CD) risk and how they interact with biological processes. This study investigates the association between environmental exposures and CD risk and evaluates their association with pre-disease biomarkers. METHODS: We studied 4289 healthy first-degree relatives (FDRs) of patients with CD from the Crohn's and Colitis Canada - Genetic, Environmental, Microbial (CCC-GEM) project. Regression models identified environmental factors associated with future CD onset and their association with pre-disease biological factors, including altered intestinal permeability measured by urinary fractional excretion of lactulose to mannitol ratio (LMR); gut inflammation via fecal calprotectin (FCP) levels; and fecal microbiome composition through 16S rRNA sequencing. RESULTS: Over a 5.62-year median follow-up, 86 FDRs developed CD. Living with a dog between ages 5 and 15 (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.40-0.96; P = .034), and living with a large family size in the first year of life (HR, 0.43; 95% CI, 0.21-0.85; P = .016) were associated with decreased CD risk, whereas having a bird at the time of recruitment (HR, 2.78; 95% CI, 1.36-5.68; P = .005) was associated with an increased CD risk. Furthermore, living with a dog was associated with reduced LMR, altered relative abundance of multiple bacterial genera, and increased Chao1 diversity, whereas bird owners had higher FCP levels. Large family during participants' first year of life was associated with altered microbiota composition without affecting FCP or LMR. CONCLUSION: This study identifies environmental variables associated with CD risk. These variables were also associated with altered barrier function, subclinical inflammation, and gut microbiome composition shifts, suggesting potential roles in CD pathogenesis.

Landscape of TPMT and NUDT15 Pharmacogenetic Variation in a Cohort of Canadian Pediatric Inflammatory Bowel Disease Patients.

BACKGROUND: Patients with inflammatory bowel disease (IBD) exhibit considerable interindividual variability in medication response, highlighting the need for precision medicine approaches to optimize and tailor treatment. Pharmacogenetics (PGx) offers the ability to individualize dosing by examining genetic factors underlying the metabolism of medications such as thiopurines. Pharmacogenetic testing can identify individuals who may be at risk for thiopurine dose-dependent adverse reactions including myelosuppression. We aimed to evaluate PGx variation in genes supported by clinical guidelines that inform dosing of thiopurines and characterize differences in the distribution of actionable PGx variation among diverse ancestral groups. METHODS: Pharmacogenetic variation in TPMT and NUDT15 was captured by genome-wide genotyping of 1083 pediatric IBD patients from a diverse Canadian cohort. Genetic ancestry was inferred using principal component analysis. The proportion of PGx variation and associated metabolizer status phenotypes was compared across 5 genetic ancestral groups within the cohort (Admixed American, African, East Asian, European, and South Asian) and to prior global estimates from corresponding populations. RESULTS: Collectively, 11% of the cohort was categorized as intermediate or poor metabolizers of thiopurines, which would warrant a significant dose reduction or selection of alternate therapy. Clinically actionable variation in TPMT was more prevalent in participants of European and Admixed American/Latino ancestry (8.7% and 7.5%, respectively), whereas variation in NUDT15 was more prevalent in participants of East Asian and Admixed American/Latino ancestry (16% and 15% respectively). CONCLUSIONS: These findings demonstrate the considerable interpopulation variability in PGx variation underlying thiopurine metabolism, which should be factored into testing diverse patient populations.

In a large, pediatric inflammatory bowel disease cohort comprised of 5 genetic ancestry groups, we evaluated the distribution of loss-of-function pharmacogenetic variants in TPMT and NUDT15 and predicted phenotypes (impact on thiopurine metabolism).

Using Deep Learning to Automate Eosinophil Counting in Pediatric Ulcerative Colitis Histopathological Images.

Background: Accurate identification of inflammatory cells from mucosal histopathology images is important in diagnosing ulcerative colitis. The identification of eosinophils in the colonic mucosa has been associated with disease course. Cell counting is not only time-consuming but can also be subjective to human biases. In this study we developed an automatic eosinophilic cell counting tool from mucosal histopathology images, using deep learning. Method: Four pediatric IBD pathologists from two North American pediatric hospitals annotated 530 crops from 143 standard-of-care hematoxylin and eosin (H & E) rectal mucosal biopsies. A 305/75 split was used for training/validation to develop and optimize a U-Net based deep learning model, and 150 crops were used as a test set. The U-Net model was then compared to SAU-Net, a state-of-the-art U-Net variant. We undertook post-processing steps, namely, (1) the pixel-level probability threshold, (2) the minimum number of clustered pixels to designate a cell, and (3) the connectivity. Experiments were run to optimize model parameters using AUROC and cross-entropy loss as the performance metrics. Results: The F1-score was 0.86 (95%CI:0.79-0.91) (Precision: 0.77 (95%CI:0.70-0.83), Recall: 0.96 (95%CI:0.93-0.99)) to identify eosinophils as compared to an F1-score of 0.2 (95%CI:0.13-0.26) for SAU-Net (Precision: 0.38 (95%CI:0.31-0.46), Recall: 0.13 (95%CI:0.08-0.19)). The inter-rater reliability was 0.96 (95%CI:0.93-0.97). The correlation between two pathologists and the algorithm was 0.89 (95%CI:0.82-0.94) and 0.88 (95%CI:0.80-0.94) respectively. Conclusion: Our results indicate that deep learning-based automated eosinophilic cell counting can obtain a robust level of accuracy with a high degree of concordance with manual expert annotations.

Pre-Diagnosis Diet Predicts Response to Exclusive Enteral Nutrition and Correlates with Microbiome in Pediatric Crohn Disease.

Exclusive enteral nutrition (EEN) is effective in inducing remission in pediatric Crohn disease (CD). EEN alters the intestinal microbiome, but precise mechanisms are unknown. We hypothesized that pre-diagnosis diet establishes a baseline gut microbiome, which then mediates response to EEN. We analyzed prospectively recorded food frequency questionnaires (FFQs) for pre-diagnosis dietary patterns. Fecal microbiota were sequenced (16SrRNA) at baseline and through an 18-month follow-up period. Dietary patterns, Mediterranean diet adherence, and stool microbiota were associated with EEN treatment outcomes, disease flare, need for anti-tumor necrosis factor (TNF)-α therapy, and long-term clinical outcomes. Ninety-eight patients were included. Baseline disease severity and microbiota were associated with diet. Four dietary patterns were identified by FFQs; a "mature diet" high in fruits, vegetables, and fish was linked to increased baseline microbial diversity, which was associated with fewer disease flares (p < 0.05) and a trend towards a delayed need for anti-TNF therapy (p = 0.086). Baseline stool microbial taxa were increased (Blautia and Faecalibacterium) or decreased (Ruminococcus gnavus group) with the mature diet compared to other diets. Surprisingly, a "pre-packaged" dietary pattern (rich in processed foods) was associated with delayed flares in males (p < 0.05). Long-term pre-diagnosis diet was associated with outcomes of EEN therapy in pediatric CD; diet-microbiota and microbiota-outcome associations may mediate this relationship.

Operating Properties of Disease Activity Indices in Pediatric Inflammatory Bowel Disease: A Systematic Review.

BACKGROUND: Accurate, reliable, and responsive disease activity indices are important to streamline drug approval and treatment modalities for pediatric inflammatory bowel disease (pIBD). We aimed to identify all scoring indices used in pIBD randomized controlled trials (RCTs) and to evaluate their operating properties. METHODS: MEDLINE, EMBASE, and CENTRAL were searched on December 6, 2022, to identify studies evaluating clinical, endoscopic, imaging, or patient-reported outcome measures (PROMs) in pIBD including Crohn's disease (CD) and ulcerative colitis (UC). Validity, reliability, responsiveness, and feasibility were summarized. RESULTS: Seventy RCTs evaluating pIBD indices were identified. Forty-one studies reported on the operating properties of 14 eligible indices (n = 9 CD, n = 5 UC). The Pediatric Crohn's Disease Activity Index (PCDAI) varied widely in terms of validity and reliability and was less feasible overall. In contrast, the Mucosal Inflammation Noninvasive Index, which includes fecal calprotectin, had better operating properties than the PCDAI. The Simplified Endoscopic Mucosal Assessment of Crohn's Disease appears more feasible and had similar operating properties than the longer Simple Endoscopic Score for Crohn's Disease. The Pediatric Ulcerative Colitis Activity Index was feasible, valid, and reliable, but responsiveness needs to be evaluated further. The Endoscopic Mayo score and the Ulcerative Colitis Endoscopic Index of Severity were reliable, but validity and responsiveness need to be evaluated further. Imaging and PROMs/quality of life indices need further evaluation. CONCLUSIONS: The operating properties of pIBD clinical trial end points varied widely. These results highlight the need for further validation and development of novel indices.

The operating properties of pediatric inflammatory bowel disease clinical trial end points varied widely. These results highlight the need for further validation and development of novel indices in this population.

Outcomes in Adult Inflammatory Bowel Disease Clinical Trials: Assessment of Similarity Among Participants with Adolescent-onset and Adult-onset Disease.

BACKGROUND AND AIMS: Most paediatric inflammatory bowel disease [IBD] studies are performed after medications are approved in adults, and the majority of participants in these studies are adolescents. We hypothesised that adolescent-onset IBD is not fundamentally different from adult-onset IBD. If this is correct, the value of delaying access to novel drugs in adolescents becomes questioned. METHODS: Data from 11 randomised, double-blind, placebo-controlled, adult Phases 2 and 3 trials of four biologics were analysed. Participants were categorised as having adolescent- or adult-onset disease [diagnosed 12 to <18, or ≥18 years]. Multivariable modelling explored the association between age at diagnosis and response to treatment, after adjustment for disease duration, extent, and severity at baseline. Data from dose arms were pooled to evaluate similarity of therapeutic response between adolescent- and adult-onset IBD within the same trial [not between doses or across trials]. Ratios of odds ratios [ORs] between the two groups were evaluated. RESULTS: Data from 6283 study participants (2575 with Crohn's disease [CD], 3708 with ulcerative colitis [UC]) were evaluated. Of 2575 study participants with CD, 325 were 12-<18 years old at diagnosis; 836 participants [32.4%] received placebo. Of 3708 participants with UC, 221 were 12-<18 years old at diagnosis; 1212 [33%] were receiving placebo. The majority of the ratios of ORs were within 2-fold, suggesting that responses in adolescent- and adult-onset participants are generally similar. CONCLUSION: Data presented lend support for extrapolating efficacy of biologics from adults to adolescents with IBD, which would facilitate earlier labelling and patient access.

Variation in the Care of Children with Inflammatory Bowel Disease Within and Across Canadian Provinces: A Multi-Province Population-Based Cohort Study.

Purpose: The incidence of childhood-onset inflammatory bowel disease (IBD) is rising. We described variation in health services utilization and need for surgery among children with IBD between six and 60 months following IBD diagnosis across Canadian pediatric centers and evaluated the associations between care provided at diagnosis at each center and the variation in these outcomes. Patients and Methods: Using population-based deterministically-linked health administrative data from four Canadian provinces (Alberta, Manitoba, Nova Scotia, Ontario) we identified children diagnosed with IBD <16 years of age using validated algorithms. Children were assigned to a pediatric center of care using a hierarchical approach based on where they received their initial care. Outcomes included IBD-related hospitalizations, emergency department (ED) visits, and IBD-related abdominal surgery occurring between 6 and sixty months after diagnosis. Mixed-effects meta-analysis was used to pool results and examine the association between center-level care provision and outcomes. Results: We identified 3784 incident cases of pediatric IBD, of whom 2937 (77.6%) were treated at pediatric centers. Almost a third (31.4%) of children had ≥1 IBD-related hospitalization and there were 0.66 hospitalizations per person during follow-up. More than half (55.8%) of children had ≥1 ED visit and there were 1.64 ED visits per person. Between-center heterogeneity was high for both outcomes; centers where more children visited the ED at diagnosis had more IBD-related hospitalizations and more ED visits during follow-up. Between-center heterogeneity was high for intestinal resection in Crohn's disease but not colectomy in ulcerative colitis. Conclusion: There is variation in health services utilization among children with IBD and risk of undergoing intestinal resection in those with Crohn's disease, but not colectomy among children with ulcerative colitis, across Canadian pediatric tertiary-care centers. Improvements in clinical care pathways are needed to ensure all children have equitable and timely access to high quality care.

Health Services Utilization and Specialist Care in Pediatric Inflammatory Bowel Disease: A Multiprovince Population-Based Cohort Study.

BACKGROUND: Patterns of health services utilization among children with inflammatory bowel disease (IBD) are important to understand as the number of children with IBD continues to increase. We compared health services utilization and surgery among children diagnosed <10 years of age (Paris classification: A1a) and between 10 and <16 years of age (A1b). METHODS: Incident cases of IBD diagnosed <16 years of age were identified using validated algorithms from deterministically linked health administrative data in 5 Canadian provinces (Alberta, Manitoba, Nova Scotia, Ontario, Quebec) to conduct a retrospective cohort study. We compared the frequency of IBD-specific outpatient visits, emergency department visits, and hospitalizations across age groups (A1a vs A1b [reference]) using negative binomial regression. The risk of surgery was compared across age groups using Cox proportional hazards models. Models were adjusted for sex, rural/urban residence location, and mean neighborhood income quintile. Province-specific estimates were pooled using random-effects meta-analysis. RESULTS: Among the 1165 (65.7% Crohn's) children with IBD included in our study, there were no age differences in the frequency of hospitalizations (rate ratio [RR], 0.88; 95% confidence interval [CI], 0.74-1.06) or outpatient visits (RR, 0.95; 95% CI, 0.78-1.16). A1a children had fewer emergency department visits (RR, 0.70; 95% CI, 0.50-0.97) and were less likely to require a Crohn's-related surgery (hazard ratio, 0.49; 95% CI, 0.26-0.92). The risk of colectomy was similar among children with ulcerative colitis in both age groups (hazard ratio, 0.71; 95% CI, 0.49-1.01). CONCLUSIONS: Patterns of health services utilization are generally similar when comparing children diagnosed across age groups.

Among 1165 children with inflammatory bowel disease, health services utilization was similar for children diagnosed <10 years of age and those diagnosed ≥10 years of age, except younger children had fewer emergency department visits and Crohn's disease­related surgeries.

Fatigue in pediatric inflammatory bowel diseases: A systematic review and a single center experience.

OBJECTIVES: We aimed to review the literature on fatigue in pediatric inflammatory bowel diseases (PIBD), to explore how it is measured, and approximate its rate in an inception pediatric cohort. METHODS: Studies on fatigue were systematically reviewed and selected by two authors. Next, we retrieved the two fatigue-related questions of the IMPACT-III questionnaire at 4 and 12 months after diagnosis from a prospectively maintained cohort of PIBD patients, each scoring 0-100 (lower scores imply more fatigue), and 44 healthy controls. RESULTS: The systematic review identified 14 studies reporting fatigue in children, of which nine had fatigue as the primary outcome and only two provided rates of fatigue. No standalone index was identified for measuring fatigue specifically for PIBD. Of 80 children included in the inception cohort, 62 (78%) scored an average of ≤75 on the two IMPACT-III questions (approximating at least mild fatigue), 26 (33%) scored ≤50 (at least moderate fatigue) and nine (11%) scored ≤25 (severe fatigue). In comparison, only four (9%) healthy children scored at least moderate fatigue (p = 0.007). Fatigue rates at 12 months were only slightly and nonsignificantly lower. Fatigue of any severity was reported in 92% children with active disease versus 63% of those in clinical remission (p = 0.01). CONCLUSION: Literature reporting on fatigue in PIBD is scarce, and no PIBD-specific tool is available to measure fatigue. In our cohort, fatigue-related questions were frequently scored low in children with IBD, mainly among children with active disease but also during clinical remission.

Linking microbial genes to plasma and stool metabolites uncovers host-microbial interactions underlying ulcerative colitis disease course.

Understanding the role of the microbiome in inflammatory diseases requires the identification of microbial effector molecules. We established an approach to link disease-associated microbes to microbial metabolites by integrating paired metagenomics, stool and plasma metabolomics, and culturomics. We identified host-microbial interactions correlated with disease activity, inflammation, and the clinical course of ulcerative colitis (UC) in the Predicting Response to Standardized Colitis Therapy (PROTECT) pediatric inception cohort. In severe disease, metabolite changes included increased dipeptides and tauro-conjugated bile acids (BAs) and decreased amino-acid-conjugated BAs in stool, whereas in plasma polyamines (N-acetylputrescine and N1-acetylspermidine) increased. Using patient samples and Veillonella parvula as a model, we uncovered nitrate- and lactate-dependent metabolic pathways, experimentally linking V. parvula expansion to immunomodulatory tryptophan metabolite production. Additionally, V. parvula metabolizes immunosuppressive thiopurine drugs through xdhA xanthine dehydrogenase, potentially impairing the therapeutic response. Our findings demonstrate that the microbiome contributes to disease-associated metabolite changes, underscoring the importance of these interactions in disease pathology and treatment.

Outcomes Following Acute Severe Colitis at Initial Presentation: A Multi-centre, Prospective, Paediatric Cohort Study.

AIM: To assess contemporary outcomes in children with acute severe ulcerative colitis [ASUC] at initial presentation. METHODS: Between April 2014 and January 2019, children aged <17 years, with new onset ASUC (Paediatric Ulcerative Colitis Activity Index [PUCAI ≥65) were prospectively followed in a Canadian inception cohort study. 16S rRNA amplicon sequencing captured microbial composition of baseline faecal samples. Primary endpoint was corticosteroid-free clinical remission with intact colon at 1 year [PUCAI <10, no steroids ≥4 weeks]. RESULTS: Of 379 children with new onset UC/IBD-unclassified, 105 [28%] presented with ASUC (42% male; median [interquartile range; [IQR]) age 14 [11-16] years; extensive colitis in all). Compared with mild UC, gut microbiome of ASUC patients had lower α-diversity, decreased beneficial anaerobes, and increased aerobes; 54 [51%] children were steroid-refractory and given infliximab [87% intensified regimen]. Corticosteroid-free remission at 1 year was achieved by 62 [61%] ASUC cohort (by 34 [63%] steroid-refractory patients, all on biologics; by 28 [55%] steroid responders,13 [25%] on 5- aminosalicylic acid [5-ASA], 5 [10%] on thiopurines, 10 [20%] on biologics). By 1 year, 78 [74%] escalated to infliximab including 24 [47%] steroid-responders failed by 5-ASA and/or thiopurines. In multivariable analysis, clinical predictors for commencing infliximab included hypoalbuminaemia, greater PUCAI, higher age, and male sex. Over 18 months, repeat corticosteroid course[s] and repeat hospitalisation were less likely among steroid-refractory versus -responsive but -dependent patients (adjusted odds ratio [aOR] 0.71 [95% CI 0.57-0.89] and 0.54 [95% CI 0.45-0.66], respectively). CONCLUSION: The majority of children presenting with ASUC escalate therapy to biologics. Predictors of need for advanced therapy may guide selection of optimal maintenance therapy.