This article is the second in a series of two publications relating to the European Crohns and Colitis Organisation [ECCO] evidence-based consensus on the management of Crohns disease. The first article covers medical management; the present article addresses surgical management, including preoperative aspects and drug management before surgery. It also provides technical advice for a variety of common clinical situations. Both articles together represent the evidence-based recommendations of the ECCO for Crohns disease and an update of previous guidelines.

Background and Aims: Diagnosis and management of inflammatory bowel diseases [IBD] requires a lifelong multidisciplinary approach.The quality of medical reporting is crucial in this context.The present topical review addresses the need for optimised reporting in endoscopy, surgery, and histopathology. Methods: A consensus expert panel consisting of gastroenterologists, surgeons, and pathologists, convened by the European Crohns and Colitis Organisation, performed a systematic literature review. The following topics were covered: in endoscopy: [i] general IBD endoscopy; [ii] disease activity and surveillance; [iii] endoscopy treatment in IBD; in surgery: [iv] medical history with surgical relevance, surgical indication, and strategy; [v] operative approach; [vi] intraoperative disease description; [vii] operative steps; in pathology: [viii] macroscopic assessment and interpretation of resection specimens; [ix] IBD histology, including biopsies, surgical resections, and neoplasia; [x] IBD histology conclusion and report. Statements were developed using a Delphi methodology incorporating two consecutive rounds. Current practice positions were set when >= 80% of participants agreed on a recommendation. Results: Thirty practice positions established a standard terminology for optimal reporting in endoscopy, surgery, and histopathology. Assessment of disease activity, surveillance recommendations, advice to surgeons for operative indication and strategies, including margins and extent of resection, and diagnostic criteria of IBD, as well as guidance for the interpretation of dysplasia and cancer, were handled. A standardised report including a core set of items to include in each specialty report, was defined. Conclusions: Interdisciplinary high-quality care requires thorough and standardised reporting across specialties.This topical review offers an actionable framework and practice recommendations to optimise reporting in endoscopy, surgery, and histopathology.

This article is the second in a series of two publications on the European Crohn's and Colitis Organisation [ECCO] evidence-based consensus on the management of Crohn's disease. The first article covers medical management; the present article addresses surgical management, including preoperative aspects and drug management before surgery. It also provides technical advice for a variety of common clinical situations. Both articles together represent the evidence-based recommendations of the ECCO for Crohn's disease and an update of prior ECCO Guidelines.

INTRODUCTION:

Ileal pouch anal anastomosis (IPAA) is the standard procedure for reconstruction after colectomy for ulcerative colitis (UC). However, ileorectal anastomosis (IRA) as an alternative has, recently experienced a revival. This study from a single center compares the clinical outcomes of these procedures.

METHODS:

From 1992 to 2006, 253 patients consecutively underwent either IRA (n=105) or IPAA (n=148). Selection to either procedure was determined on the basis of rectal inflammation, presence of dysplasia/cancer or patient preferences. Patient-records were retrospectively evaluated. Mean follow-up time was 5.4 and 6.3 years respectively.

RESULTS:

Major postoperative complications occurred in 12.4% of patients after IRA and in 12.8% after IPAA (ns). Complications of any kind after IRA or IPAA, even including subsequent stoma-closure, occurred in 23.8% and 39.9% respectively (p<0.01). Estimated cumulative failure rates after 5 and 10 years were 10.1% and 24.1% for IRA and 6.1% and 18.6% for IPAA respectively (ns). The most common cause for failure was intractable proctitis (4.8%) and unspecified dysfunction (4.8%) respectively. At follow-up 76.9% of patients with IRA had proctitis and 34.1% with IPAA had pouchitis. Estimated cumulative cancer-risk after 10, 20 and 25 year duration of disease was 0.0%, 2.1% and 8.7% for IRA. Figures for IPAA were 0.7%, 1.8% and 1.8% (ns).

CONCLUSION:

Failure-rates did not significantly differ between patients operated with IRA or IPAA. Patients operated with IPAA had a higher cumulative number of postoperative complications. The high long-term cancer-risk after IRA indicates that this procedure should be an interim solution in younger patients.

Background: Inflammatory bowel disease [IBD] has been linked to an increased risk of colorectal neoplasia. However, the types and risks of specific polyp types in IBD are less clear. Methods: We identified 41 880 individuals with IBD (Crohns disease [CD: n = 12 850]; ulcerative colitis [UC]: n = 29 030]) from Sweden matched with 41 880 reference individuals. Using Cox regression, we calculated adjusted hazard ratios [aHRs] for neoplastic colorectal polyps [tubular, serrated/sessile, advanced and villous] defined by histopathology codes. Results: During follow-up, 1648 [3.9%] IBD patients and 1143 [2.7%] reference individuals had an incident neoplastic colorectal polyp, corresponding to an incidence rate of 46.1 and 34.2 per 10 000 person-years, respectively. This correlated to an aHR of 1.23 (95% confidence interval [CI] 1.12-1.35) with the highest HRs seen for sessile serrated polyps [8.50, 95% CI 1.10-65.90] and traditional serrated adenomas [1.72, 95% CI 1.02-2.91]. aHRs for colorectal polyps were particularly elevated in those diagnosed with IBD at a young age and at 10 years after diagnosis. Both absolute and relative risks of colorectal polyps were higher in UC than in CD [aHRs 1.31 vs 1.06, respectively], with a 20-year cumulative risk difference of 4.4% in UC and 1.5% in CD, corresponding to one extra polyp in 23 patients with UC and one in 67 CD patients during the first 20 years after IBD diagnosis. Conclusions: In this nationwide population-based study, there was an increased risk of neoplastic colorectal polyps in IBD patients. Colonoscopic surveillance in IBD appears important, especially in UC and after 10 years of disease.

Aims: i] To evaluate the evolution of pregnancies and offspring after inflammatory bowel disease [IBD] surgery during pregnancy; and ii] to describe the indications, the surgical techniques, and the frequency of caesarean section concomitant with surgery.

Methods: Patients operated on due to IBD during pregnancy after 1998 were included. Participating clinicians were asked to review their databases to identify cases. Data on patients demographics, IBD characteristics, medical treatments, IBD activity, pregnancy outcomes, surgery, delivery, and foetal and maternal outcomes, were recorded.

Results: In all, 44 IBD patients were included, of whom 75% had Crohns disease; 18% of the surgeries were performed in the first trimester, 55% in the second, and 27% in the third trimester. One patient had complications during surgery, and 27% had postsurgical complications. No patient died. Of deliveries, 70% were carried out by caesarean section. There were 40 newborns alive. There were four miscarriages/stillbirths [one in the first, two in the second, and one in the third trimester]; two occurred during surgery, and another two occurred 2 weeks after surgery; 14% of the surgeries during the second trimester and 64% of those in the third trimester ended up with a simultaneous caesarean section or vaginal delivery. Of the 40 newborns, 61% were premature and 47% had low birth weight; 42% of newborns needed hospitalisation [25% in the intensive care unit].

Conclusions: IBD surgery during pregnancy remains an extremely serious situation. Therefore, surgical management should be performed in a multidisciplinary team, involving gastroenterologists, colorectal surgeons, obstetricians, and neonatal specialists.

Background and Aims Crohns disease [CD] is a debilitating, inflammatory condition affecting the gastrointestinal tract. There is no cure and sustained clinical and endoscopic remission is achieved by fewer than half of patients with current therapies. The immunoregulatory function of the vagus nerve, the inflammatory reflex, has been established in patients with rheumatoid arthritis and biologic-naive CD. The aim of this study was to explore the safety and efficacy of vagus nerve stimulation in patients with treatment-refractory CD, in a 16-week, open-label, multicentre, clinical trial.Methods A vagus nerve stimulator was implanted in 17 biologic drug-refractory patients with moderately to severely active CD. One patient exited the study pre-treatment, and 16 patients were treated with vagus nerve stimulation [4/16 receiving concomitant biologics] during 16 weeks of induction and 24 months of maintenance treatment. Endpoints included clinical improvement, patient-reported outcomes, objective measures of inflammation [endoscopic/molecular], and safety.Results There was a statistically significant and clinically meaningful decrease in CD Activity Index at Week 16 [mean +/- SD: -86.2 +/- 92.8, p = 0.003], a significant decrease in faecal calprotectin [-2923 +/- 4104, p = 0.015], a decrease in mucosal inflammation in 11/15 patients with paired endoscopies [-2.1 +/- 1.7, p = 0.23], and a decrease in serum tumour necrosis factor and interferon-gamma [46-52%]. Two quality-of-life indices improved in 7/11 patients treated without biologics. There was one study-related severe adverse event: a postoperative infection requiring device explantation.Conclusions Neuroimmune modulation via vagus nerve stimulation was generally safe and well tolerated, with a clinically meaningful reduction in clinical disease activity associated with endoscopic improvement, reduced levels of faecal calprotectin and serum cytokines, and improved quality of life. Graphical Abstract

Despite the introduction of potent biologic therapies, many patients with Crohns disease [CD] still require an ileocolonic resection [ICR] during the course of their disease. Furthermore, the need of redo ICR has not decreased over the past few decades, highlighting the need for better strategies to prevent and treat postoperative recurrence [POR]. The first step to develop such a strategy would be to define and standardise the description of POR with adequate diagnostic instruments. In this article, we will describe the different methodologies used to report POR [endoscopic, histological, radiological, biochemical, clinical, and surgical], and review their potential benefits and limitations, as well as the optimal timing of evaluation.

Background and Aims: Inflammatory bowel disease [IBD] has been associated with reduced female fertility. We analyse fertility in a national cohort of women with IBD.

Methods: Fertility was assessed in women with IBD aged 15-44 years in 1964-2014, identified from the Swedish National Patient Register and a matched cohort [ratio 1:5]. Patients with indeterminate colitis or inconsistent IBD coding were classified as IBD-unclassified [IBD-U].

Results: The cohorts included 27 331 women with IBD and 131 892 matched individuals. The fertility rate in IBD was 1.52 (standard deviation [SD] 1.22) births per 1000 person-years and 1.62 [SD 1.28] [p&lt;0.001] in matched individuals. Fertility was impaired in all IBD subtypes compared with the matched cohort (hazard ratio Crohns disease [CD] 0.88, 95% confidence interval [CI] 0.85-0.91; IBD-U 0.86, 95% CI 0.83-0.89; and ulcerative colitis [UC] 0.96, 95% CI 0.93-0.98). Fertility improved during the study period for the IBD cohort except for CD. Parity progression ratio, the proportion of IBD women progressing from one parity to the next compared with the matched cohort, was decreased at all parity levels for CD and IBD-U, but only for multiparous women in UC. Contraceptive usage was higher in IBD, both before and after the diagnosis. Disease severity, bowel resections, and perianal disease in CD affected fertility negatively.

Conclusions: Fertility was impaired mainly in women with CD and IBD-U, and less so in UC. During the study period, fertility improved in women with UC or IBD-U. Some results suggest a role of voluntarily reduced fertility.

BACKGROUND AND AIMS: Colectomy and reconstruction in patients with inflammatory bowel disease (IBD) may adversely affect fertility, but few population-based studies are available.

METHODS: Fertility was assessed in 2,989 women and 3,771 men with IBD and prior colectomy 1964-2014, identified from the Swedish National Patient Register, and 35,092 matched individuals.

RESULTS: Reconstruction with ileoanal pouch anastomosis (IPAA) was as common as ileorectal anastomosis (IRA) in ulcerative colitis (UC) and IBD-unclassified (IBD-U) while rare in Crohn's disease (CD). Compared with the matched reference cohort, women with IBD had lower fertility overall after colectomy (HR 0.65, CI 0.61-0.69), with least impact leaving the rectum intact (HR 0.79, CI 0.70-0.90). Compared with colectomy only, fertility in female patients remained unaffected after IRA (HR 0.86, CI 0.63-1.17 for UC, 0.86, CI 0.68-1.08 for IBD-U and 1.07, CI 0.70-1.63 for CD), but was impaired after IPAA, especially in UC (HR 0.67CI 0.50-0.88), and after completion proctectomy (HR 0.65, CI 0.49-0.85 for UC, 0.68, CI 0.55-0.85 for IBD-U and 0.61, CI 0.38-0.96 for CD). In men, fertility was marginally reduced post colectomy (HR 0.89, CI 0.85-0.94), regardless of reconstruction.

CONCLUSIONS: Fertility was reduced in women after colectomy for IBD. The least impact was seen when a deviated rectum was left intact. IRA was associated with no further reduction in fertility, whereas proctectomy and IPAA were associated with the strongest impairment. IRA therefore seems to be the preferred reconstruction to preserve fertility in selected female patients. Fertility in men was only moderately reduced after colectomy.

BACKGROUND AND AIMS: Diarrhoea is a common, debilitating symptom of gastrointestinal disorders. Pathomechanisms probably involve defects in trans-epithelial water transport, but the role of aquaporin [AQP] family water channels in diarrhoea-predominant diseases is unknown. We investigated the involvement of AQPs in the pathobiology of collagenous colitis [CC], which features chronic, watery diarrhoea despite overtly normal intestinal epithelial cells [IECs].

METHODS: We assessed the expression of all AQP family members in mucosal samples of CC patients before and during treatment with the corticosteroid drug budesonide, steroid-refractory CC patients and healthy controls. Samples were analysed by genome-wide mRNA sequencing [RNA-seq] and quantitative real-time PCR [qPCR]. In some patients, we performed tissue microdissection followed by RNA-seq to explore the IEC-specific CC transcriptome. We determined changes in the protein levels of the lead candidates in IEC by confocal microscopy. Finally, we investigated the regulation of AQP expression by corticosteroids in model cell lines.

RESULTS: Using qPCR and RNA-seq, we identified loss of AQP8 expression as a hallmark of active CC, which was reverted by budesonide treatment in steroid-responsive but not refractory patients. Consistently, decreased AQP8 mRNA and protein levels were observed in IECs of patients with active CC, and steroid drugs increased AQP8 expression in model IECs. Moreover, low APQ8 expression was strongly associated with higher stool frequency in CC patients.

CONCLUSION: Down-regulation of epithelial AQP8 may impair water resorption in active CC, resulting in watery diarrhoea. Our results suggest that AQP8 is a potential drug target for the treatment of diarrhoeal disorders.

Background and Aims: Crohns disease may affect the ability to work and lead to permanent disability. We aimed to investigate work loss in prevalent patients. Methods: We identified patients with Crohns disease and general population comparators matched by sex, birth year, healthcare region and education. We assessed days of sick leave and disability pension retrieved from the Swedish Social Insurance Agency and estimated the absolute and relative risk of receiving disability pension [minimum 25% work impairment]. Results: In 2014, the 20 638 Crohns disease patients [median age 44 years] had more than twice as many mean lost workdays [disability pension: 44; sick leave: 19] as the 102 038 comparators [disability pension: 20; sick leave: 8], mean difference 35 days [95% confidence interval 33-37]. However, the majority had no lost workdays [68% of patients and 85% of comparators]. The proportion of patients receiving disability pension was 15% (6.5% in the comparators, risk ratio 2.34 [2.25-2.43]) and was higher in all subgroups, especially in female patients [28% vs 13% in the comparators], in those with amp;lt;= 9 years of education [41% vs 23%] and in ages 60-64 years [46% vs 25%]. The relative risk of disability pension within the patient cohort [adjusted for age, sex, region and education] was higher in patients with complicated disease behaviour, extraintestinal manifestations, need of surgery or treatment with biologics. The differences between patients and comparators remained when comparing other calendar years [2006-2013]. Conclusion: Work loss was found in approximately one-third of patients. The mean number of lost workdays was twice as high as in the comparators.

Despite the introduction of biological therapies, an ileocolonic resection is often required in patients with Crohns disease [CD]. Unfortunately, surgery is not curative, as many patients will develop postoperative recurrence [POR], eventually leading to further bowel damage and a decreased quality of life. The 8th Scientific Workshop of ECCO reviewed the available scientific data on both prevention and treatment of POR in patients with CD undergoing an ileocolonic resection, dealing with conventional and biological therapies, as well as non-medical interventions, including endoscopic and surgical approaches in case of POR. Based on the available data, an algorithm for the postoperative management in daily clinical practice was developed.

Background and Aims: Innate lymphoid cells [ILC] have been suggested to play a role in inflammatory bowel disease [IBD]. Here, we investigated the ILC compartment in intestinal biopsies and blood from distinct patient groups with Crohns disease [CD] and ulcerative colitis [UC], either newly diagnosed or with disease established for at least 1 year. This approach allowed us to simultaneously investigate temporal, disease-specific, and tissue-specific changes in ILC composition in IBD. Methods: ILC subset frequencies, phenotype, and transcription factor profile in blood and intestinal biopsies were investigated by multi-parameter flow cytometry analysis. Endoscopic disease severity was judged using the ulcerative colitis endoscopic index of severity and the simple endoscopic score for Crohns disease. Results: The frequency of NKp44(+)ILC3 was decreased in inflamed tissue, both in patients with CD and those with UC, already at the time of diagnosis, and correlated with disease severity. Simultaneously, the frequency of ILC1 was increased in patients with CD, whereas the frequency of ILC2 was increased in patients with UC. However, in patients with established UC or CD, both ILC1 and ILC2 were increased. In contrast to the ILC composition in inflamed tissue, ILC in non-inflamed tissue or blood were unchanged compared with non-IBD controls. Finally, in patients undergoing treatment with an anti-alpha(4)beta(7) antibody the frequencies of ILC in peripheral blood remained unchanged. Conclusions: We report both shared and distinct changes in ILC composition depending on diagnosis and disease duration. The alterations in ILC composition in IBD occur selectively at inflamed sites in the gut.

Background and Aims: The aim of this study was to report a multicentric experience of segmental colectomy [SC] in ulcerative colitis [UC] patients without active colitis, in order to assess if SC can or cannot represent an alternative to ileal pouch-anal anastomosis [IPAA]. Methods: All UC patients undergoing SC were included. Postoperative complications according to Clavien-Dindos classification, long-term results, and risk factors for postoperative colitis and reoperation for colitis on the remnant colon, were assessed. Results: A total of 72 UC patients underwent: sigmoidectomy [n = 28], right colectomy [n = 24], proctectomy [n = 11], or left colectomy [n = 9] for colonic cancer [n = 27], diverticulitis [n = 17], colonic stenosis [n = 5], dysplasia or polyps [n = 8], and miscellaneous [n = 15]. Three patients died postoperatively and 5/69 patients [7%] developed early flare of UC within 3 months after SC. After a median follow-up of 40 months, 24/ 69 patients [35%] were reoperated after a median delay after SC of 19 months [range, 2-158 months]: 22/24 [92%] underwent total colectomy and ileorectal anastomosis [n = 9] or total coloproctectomy [TCP] [n = 13] and 2/24 [8%] an additional SC. Reasons for reoperation were: colitis [n = 14; 20%], cancer [n = 3] or dysplasia [n = 3], colonic stenosis [n = 1], and unknown reasons [n = 3]. Endoscopic score of colitis before SC was Mayo 23 in 5/5 [100%] patients with early flare vs 15/42 without early flare [36%; p = 0.0101] and in 9/12 [75%] patients with reoperation for colitis vs 11/35 without reoperation [31%; p = 0.016]. Conclusions: After segmental colectomy in UC patients, postoperative early colitis is rare [7%]. Segmental colectomy could possibly represent an alternative to IPAA in selected UC patients without active colitis.

Background and aims: The importance of efficient and safe treatment of Crohns disease is highlighted by its chronicity. Both medical and surgical treatments have shown good results in the symptomatic control of limited ileocaecal Crohns disease. The aim of this study was to compare medical treatment with surgical treatment of ileocaecal Crohns disease. Methods: Thirty-six patients from seven hospitals with primary ileocaecal Crohns disease were randomized to either medical or surgical treatment. The medical treatment was induction of remission with budesonide and thereafter maintenance treatment with azathioprine. The surgical treatment was open ileocaecal resection. Crohns disease activity index over time, expressed as area under the curve at 1, 3 and 5 years, was the primary endpoint. Subjective health measured with the 36-item Short Form Survey Instrument (SF36) and a visual analogue scale (VAS) were secondary endpoints. Results: There were no differences between the treatment groups in Crohns disease activity index over time. General health, measured as SF36 score, was higher in patients receiving surgical treatment than in those receiving medical treatment at 1 year, but there was no corresponding difference in VAS. Due to the slow inclusion rate and changes in clinical practice, the study was t = erminated prematurely. Conclusion: The study ended up being underpowered and should be interpreted with caution, but there was no clinically significant difference between the two treatment arms. Further studies are needed to address this important clinical question.

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Background and Aims Inflammatory bowel disease [IBD] is a chronic relapsing disorder of the gastrointestinal tract, which generally manifests as Crohns disease [CD] or ulcerative colitis [UC]. These subtypes are heterogeneous in terms of disease location and histological features, while sharing common clinical presentation, genetic associations and, thus, common immune regulatory pathways. Methods Using miRNA and mRNA coupled transcriptome profiling and systems biology approaches, we report a comprehensive analysis of blood transcriptomes from treatment-naive [n = 110] and treatment-exposed [n = 177] IBD patients as well as symptomatic [n = 65] and healthy controls [n = 95]. Results Broadly, the peripheral blood transcriptomes of CD and UC patients were similar. However, there was an extensive gene deregulation in the blood of IBD patients, while only a slight deregulation in symptomatic controls, when compared with healthy controls. The deregulated mRNAs and miRNAs are mainly involved in the innate immunity and are especially enriched in neutrophil activation-related pathways. Oxidative phosphorylation and neutrophil activation-related modules were found to be differentially co-expressed among treatment-naive IBD as compared to healthy controls. In the deregulated neutrophil activation-related co-expression module, IL1B was identified as the central gene. Levels of co-expression among IL1B and chemosensing receptor [CXCR1/2 and FPR1/2] genes were reduced in the blood of IBD patients when compared with healthy controls. Conclusions Immune dysregulation seen in peripheral blood transcriptomes of treatment-naive IBD patients is mainly driven by neutrophil activation.

Background and Aims Inflammatory bowel disease colitis-associated dysplasia is managed with either enhanced surveillance and endoscopic resection or prophylactic surgery. The rate of progression to cancer after a dysplasia diagnosis remains uncertain in many cases and patients have high thresholds for accepting proctocolectomy. Individualised discussion of management options is encouraged to take place between patients and their multidisciplinary teams for best outcomes. We aimed to develop a toolkit to support a structured, multidisciplinary and shared decision-making approach to discussions about dysplasia management options between clinicians and their patients. Methods Evidence from systematic literature reviews, mixed-methods studies conducted with key stakeholders, and decision-making expert recommendations were consolidated to draft consensus statements by the DECIDE steering group. These were then subjected to an international, multidisciplinary modified electronic Delphi process until an a priori threshold of 80% agreement was achieved to establish consensus for each statement. Results In all, 31 members [15 gastroenterologists, 14 colorectal surgeons and two nurse specialists] from nine countries formed the Delphi panel. We present the 18 consensus statements generated after two iterative rounds of anonymous voting. Conclusions By consolidating evidence for best practice using literature review and key stakeholder and decision-making expert consultation, we have developed international consensus recommendations to support health care professionals counselling patients on the management of high cancer risk colitis-associated dysplasia. The final toolkit includes clinician and patient decision aids to facilitate shared decision-making.

Background: Success in personalized medicine in complex disease is critically dependent on biomarker discovery. We profiled serum proteins using a novel proximity extension assay [PEA] to identify diagnostic and prognostic biomarkers in inflammatory bowel disease [IBD]. Methods: We conducted a prospective case-control study in an inception cohort of 552 patients [328 IBD, 224 non-IBD], profiling proteins recruited across six centres. Treatment escalation was characterized by the need for biological agents or surgery after initial disease remission. Nested leave-one-out cross-validation was used to examine the performance of diagnostic and prognostic proteins. Results: A total of 66 serum proteins differentiated IBD from symptomatic non-IBD controls, including matrix metallopeptidase-12 [MMP-12; Holm-adjusted p=4.1x10(-23)] and oncostatin-M [OSM; p=3.7x10(-16)]. Nine of these proteins are associated with cis-germline variation [59 independent single nucleotide polymorphisms]. Fifteen proteins, all members of tumour necrosis factor-independent pathways including interleukin-1 (IL-1) and OSM, predicted escalation, over a median follow-up of 518 [interquartile range 224-756] days. Nested cross-validation of the entire data set allowed characterization of five-protein models [96% comprising five core proteins ITGAV, EpCAM, IL18, SLAMF7 and IL8], which define a high-risk subgroup in IBD [hazard ratio 3.90, confidence interval: 2.43-6.26], or allowed distinct two- and three-protein models for ulcerative colitis and Crohns disease respectively. Conclusion: We have characterized a simple oligo-protein panel that has the potential to identify IBD from symptomatic controls and to predict future disease course. Further prospective work is required to validate our findings.

Background Epigenetic alterations may provide valuable insights into gene-environment interactions in the pathogenesis of inflammatory bowel disease [IBD]. Methods Genome-wide methylation was measured from peripheral blood using the Illumina 450k platform in a case-control study in an inception cohort (295 controls, 154 Crohns disease [CD], 161 ulcerative colitis [UC], 28 IBD unclassified [IBD-U)] with covariates of age, sex and cell counts, deconvoluted by the Houseman method. Genotyping was performed using Illumina HumanOmniExpressExome-8 BeadChips and gene expression using the Ion AmpliSeq Human Gene Expression Core Panel. Treatment escalation was characterized by the need for biological agents or surgery after initial disease remission. Results A total of 137 differentially methylated positions [DMPs] were identified in IBD, including VMP1/MIR21 [p = 9.11 x 10(-15)] and RPS6KA2 [6.43 x 10(-13)], with consistency seen across Scandinavia and the UK. Dysregulated loci demonstrate strong genetic influence, notably VMP1 [p = 1.53 x 10(-15)]. Age acceleration is seen in IBD [coefficient 0.94, p &lt; 2.2 x 10(-16)]. Several immuno-active genes demonstrated highly significant correlations between methylation and gene expression in IBD, in particular OSM: IBD r = -0.32, p = 3.64 x 10(-7) vs non-IBD r = -0.14, p = 0.77]. Multi-omic integration of the methylome, genome and transcriptome also implicated specific pathways that associate with immune activation, response and regulation at disease inception. At follow-up, a signature of three DMPs [TAP1, TESPA1, RPTOR] were associated with treatment escalation to biological agents or surgery (hazard ratio of 5.19 [CI: 2.14-12.56], logrank p = 9.70 x 10(-4)). Conclusion These data demonstrate consistent epigenetic alterations at diagnosis in European patients with IBD, providing insights into the pathogenetic importance and translational potential of epigenetic mapping in complex disease.

Background: MicroRNAs [miRNAs] are cell-specific small non-coding RNAs that can regulate gene expression and have been implicated in inflammatory bowel disease [IBD] pathogenesis. Here we define the cell-specific miRNA profiles and investigate its biomarker potential in IBD. Methods: In a two-stage prospective multi-centre case control study, next generation sequencing was performed on a discovery cohort of immunomagnetically separated leukocytes from 32 patients (nine Crohns disease [CD], 14 ulcerative colitis [UC], eight healthy controls) and differentially expressed signals were validated in whole blood in 294 patients [97 UC, 98 CD, 98 non-IBD, 1 IBDU] using quantitative PCR. Correlations were analysed with phenotype, including need for early treatment escalation as a marker of progressive disease using Cox proportional hazards. Results: In stage 1, each leukocyte subset [CD4(+) and CD8(+)T-cells and CD14(+) monocytes] was analysed in IBD and controls. Three specific miRNAs differentiated IBD from controls in CD4(+) T-cells, including miR-1307-3p [p = 0.01], miR-3615 [p = 0.02] and miR-4792 [p = 0.01]. In the extension cohort, in stage 2, miR-1307-3p was able to predict disease progression in IBD (hazard ratio [HR] 1.98, interquartile range [IQR]: 1.20-3.27; logrank p = 1.80 x 10(-3)), in particular CD [HR 2.81; IQR: 1.11-3.53, p = 6.50 x 10(-4)]. Using blood-based multimarker miRNA models, the estimated chance of escalation in CD was 83% if two or more criteria were met and 90% for UC if three or more criteria are met. Interpretation: We have identified and validated unique CD4(+) T-cell miRNAs that are differentially regulated in IBD. These miRNAs may be able to predict treatment escalation and have the potential for clinical translation; further prospective evaluation is now indicated.

Background and Aims: The aetiology of Crohns disease is poorly understood. By investigating twin pairs discordant for Crohns disease, we aimed to assess whether the dysregulated barrier represents a cause or a consequence of inflammation and to evaluate the impact of genetic predisposition on barrier function. Methods: Ileal biopsies from 15 twin pairs discordant for Crohns disease [monozygotic n = 9, dizygotic n = 6] and 10 external controls were mounted in Ussing chambers to assess paracellular permeability to (51)Chromium [Cr]-EDTA and trancellular passage to non-pathogenic E. coli K-12. Experiments were performed with and without provocation with acetylsalicylic acid. Immunofluorescence and ELISA were used to quantify the expression level of tight junction proteins. Results: Healthy co-twins and affected twins displayed increased Cr-51-EDTA permeability at 120 min, both with acetylsalicylic acid [p amp;lt; 0.001] and without [p amp;lt; 0.001] when compared with controls. A significant increase in Cr-51-EDTA flux was already seen at 20 min in healthy monozygotic co-twins compared with controls [p amp;lt;= 0.05] when stratified by zygosity, but not in healthy dizygotic co-twins. No difference in E. coli passage was observed between groups. Immunofluorescence of the tight junction proteins claudin-5 and tricellulin showed lower levels in healthy co-twins [p amp;lt; 0.05] and affected twins [p amp;lt; 0.05] compared with external controls, while ELISA only showed lower tricellulin in Crohns disease twins [p amp;lt; 0.05]. Conclusion: Our results suggest that barrier dysfunction is a primary defect in Crohns disease, since changes were predominantly seen in healthy monozygotic co-twins. Passage of E. coli seems to be a consequence of inflammation, rather than representing a primary defect.

Background and Aims: Patients with Crohns disease [CD] harbour an increased number of adherent-invasive E. coli [AIEC]. The strain LF82, identified in the ileal mucosa of CD patients, has been extensively studied for pathogenic mechanisms. However, understanding of the interaction of LF82 with the intestinal mucosa of CD patients is lacking. Methods: Here, we investigated the importance of long polar fimbriae [LPF] type 1 pili and the carcinoembryonic antigen-related cell-adhesion molecule 6 [CEACAM6] for translocation of LF82 in an in vitro model of follicle-associated epithelium [FAE], and in the FAE and villus epithelium [VE] of patients with CD and controls, using Ussing chambers. Results: Significantly greater LF82 passage occurred in the FAE model compared with in the VE Caco-2cl1 mono-culture. Moreover, bacterial translocation was inhibited by either LPF disruption or pre-incubation with anti-CEACAM6 antibody. Tissue mounted in Ussing chambers showed significantly higher LF82 passage in FAE from patients with CD compared with control FAE, that was diminished in LF82 lacking LPF and by blocking host CEACAM6. Interestingly, addition of LF82 to the CD FAE tissues significantly increased paracellular permeability [of (51)Chromium-EDTA] compared with baseline, and the increase was inhibited by anti-CEACAM6. Immunofluorescence and immunoblots showed higher expression of CEACAM6 in FAE of patients with CD compared with in FAE from controls. Conclusions: These data suggest that the FAE of CD patients is a site of vulnerability for invasion by LF82 via a mechanism that requires both bacterial LPF and host CEACAM6. Further, LF82 has the ability to increase paracellular passage through the FAE of patients with CD. These data can help define novel therapeutic targets in CD for the prevention of clinical recurrence.

Background and aims: A skewed thiopurine metabolism is a phenomenon associated with both poor treatment response and toxicity. Our aim was to evaluate the frequency of this phenomenon and the relationship to thiopurine methyltransferase (TPMT) function. less thanbrgreater than less thanbrgreater thanMethods: All thiopurine metabolite measurements in adult patients (n=4033) between January 2006 and April 2012 were assessed to evaluate the occurrence of a skewed metabolism and the relationship to TPMT genotype and activity. less thanbrgreater than less thanbrgreater thanResults: A skewed metabolism was observed in 14% of all patients. It only developed in patients with a normal TPMT genotype, but was observed at all TPMT activity levels within the normal range (9.1-24.2 U/ml RBC). Two cases that illustrate typical clinical scenarios of a skewed metabolism and the effect of combination treatment with low-dose azathioprine and allopurinol are presented. less thanbrgreater than less thanbrgreater thanConclusions: A skewed metabolism is a common clinical phenomenon in patients with a normal TPMT function, which can develop at all TPMT activity levels within the normal range. We suggest that metabolite measurements should be considered in patients not responding to treatment and in those with hepatotoxicity or myelotoxicity in order to detect a skewed metabolism, since this phenomenon can be successfully managed by a combination of low-dose azathioprine and allopurinol.

Colectomy is still frequently required in the care of ulcerative colitis. The most common indications are either non-responding colitis in the emergency setting, chronic active disease, steroid-dependent disease or neoplastic change like dysplasia or cancer. The use of the ileal pouch anal anastomosis has internationally been the gold standard, substituting the rectum with a pouch. Recently the use of the ileorectal anastomosis has increased in frequency as reconstructive method after subtotal colectomy. Data from centres using ileorectal anastomosis have shown the method to be safe, with functionality and risk of failure comparable to the ileal pouch anal anastomosis. The methods have different advantages as well as disadvantages, depending on a number of patient factors and where in life the patient is at time of reconstruction. The ileorectal anastomosis could, together with the Kock continent ileostomy, in selected cases be a complement to the ileal pouch anal anastomosis in ulcerative colitis and should be discussed with the patient before deciding on reconstructive method.

Microscopic colitis (MC) is an inflammatory bowel disease presenting with chronic, non-bloody watery diarrhoea and few or no endoscopic abnormalities. The histological examination reveals mainly two subtypes of MC, lymphocytic or collagenous colitis. Despite the fact that the incidence in MC has been rising over the last decades, research has been sparse and our knowledge about MC remains limited. Specialists in the field have initiated the European Microscopic Colitis Group (EMCG) with the primary goal to create awareness on MC. The EMCG is furthermore a forum with the intention to promote clinical and basic research. In this article statements and comments are given that all members of the EMCG have considered being of importance for a better understanding of MC. The paper focuses on the newest updates in epidemiology, symptoms and diagnostic criteria, pathophysiology and highlights some unsolved problems. Moreover, a new treatment algorithm is proposed on the basis of new evidence from well-designed, randomized control trials.

BACKGROUND: The relationship between clinical and histological parameters in collagenous colitis (CC) is poorly understood. Smoking is a risk factor for CC, whereas its impact on clinical activity and outcome is not well known.

METHODS: In a post hoc analysis of pooled data from two randomized controlled trials we assessed the association between demographic data (gender, age, smoking habits, family history of inflammatory bowel disease), clinical variables (duration of symptoms, mean number of stools/watery stools per day, abdominal pain, clinical remission) and histological data (thickness of the collagen band, inflammation of the lamina propria, total numbers of intraepithelial lymphocytes, degeneration). Moreover, we analysed the predictive value of baseline parameters for clinical outcome in a logistic regression model.

RESULTS: Pooled data were available from 202 patients with active CC, of whom 36% were current smokers, 29% former smokers and 35% non-smokers. Smoking status was associated with decreased ability to achieve clinical remission (current smokers vs non-smokers: odds ratio [OR] 0.31, 95% confidence interval [CI] 0.10-0.98, p = 0.045; former smokers vs non-smokers: OR 0.19, 95% CI 0.05-0.73, p = 0.016). Current smokers had an increased mean number of watery stools at baseline compared with non-smokers (p = 0.051) and increased mean number of watery stools per se was associated with decreased likelihood of obtaining clinical remission (OR 0.63, 95% CI 0.47-0.86, p = 0.003). Patient characteristics and histology at baseline had no association with clinical parameters and no predictive value for clinical outcome.

CONCLUSION: Smoking worsens clinical symptoms in CC and is associated with an increased number of watery stools and decreased likelihood of achieving clinical remission. There is no significant association between histology and clinical data.

Previous studies describing the cumulative failure rate after reconstructive surgery in patients with inflammatory bowel disease have been restricted to specific hospitals, and the generalizability of these results in a population-based setting is unknown. The aim of this study was to investigate the cumulative failure rate and risk factors for failure after reconstructive surgery in patients with inflammatory bowel disease. The study cohort includes all patients with inflammatory bowel disease in Sweden who underwent colectomy in 2000 through 2013 who were later treated with reconstructive surgery with ileal pouch-anal anastomosis or ileorectal anastomosis. Each patient was followed from admission for reconstructive surgery until admission for failure (a diverting stoma or permanent stoma), date of death, migration or December 31, 2013. Cumulative failure distributions were obtained with the Kaplan-Meier method, and multivariable Cox regression models were used to calculate the risk of failure. Of the 1809 patients with inflammatory bowel disease treated with colectomy and reconstructive surgery, 83% had ulcerative colitis. During follow-up, 270 patients failed, and the cumulative failure rate was 4.1%, 13.2%, and 15.3% after 1, 3, and 5 years, respectively. The risk of failure was lower after treatment with ileal pouch-anal anastomosis than with ileorectal anastomosis [hazard ratio (95% confidence interval): 0.72 (0.56-0.93)]. Gender, hospital volume, and timing of reconstruction were not significantly associated with the risk of failure. The 5-year cumulative failure rate in a nationwide setting was 15.3%, and hospital volume was not associated with the risk of failure.

Background and Aims

The incidence of childhood-onset [< 18 years] inflammatory bowel disease [IBD] is increasing worldwide, and some studies suggest that it represents a more severe disease phenotype. Few nationwide, population-based studies have evaluated the surgical burden in patients with childhood-onset IBD, and whether the improved medical treatment has influenced the need for gastrointestinal surgery. The aim was to examine whether the surgical treatment at any age of patients with childhood-onset IBD has changed over time.

Methods

In a nationwide cohort study we identified 4695 children [< 18 years] diagnosed with incident IBD in 2002–2014 through the Swedish Patient Register [ulcerative colitis: n = 2295; Crohn’s disease: n = 2174; inflammatory bowel disease-unclassified: n = 226]. Abdominal [intestinal resections and colectomies] and perianal surgeries were identified through the Swedish Patient Register. The cumulative incidences of surgeries were calculated using the Kaplan-Meier method.

Results

In the cohort, 44% were females and 56% males. The median age at inflammatory bowel disease diagnosis was 15 years and the maximum age at end of follow-up was 31 years. The 3-year cumulative incidence of intestinal surgery was 5% in patients with ulcerative colitis and 7% in patients with Crohn’s disease, and lower in children aged < 6 years at inflammatory bowel disease diagnosis [3%] than in those aged 15–17 years at diagnosis [7%]. Calendar period of inflammatory bowel disease diagnosis was not associated with risk of surgery.

Conclusion

Over the past 13 years, the risk of surgery in childhood-onset inflammatory bowel disease has remained unchanged.

Aim To assess the pathobiological and translational importance of whole-blood transcriptomic analysis in inflammatory bowel disease [IBD]. Methods We analysed whole-blood expression profiles from paired-end sequencing in a discovery cohort of 590 Europeans recruited across six countries in the IBD Character initiative (newly diagnosed patients with Crohns disease [CD; n = 156], ulcerative colitis [UC; n = 167], and controls [n = 267]), exploring differential expression [DESeq2], co-expression networks [WGCNA], and transcription factor involvement [EPEE, ChEA, DoRothEA]. Findings were validated by analysis of an independent replication cohort [99 CD, 100 UC, 95 controls]. In the discovery cohort, we also defined baseline expression correlates of future treatment escalation using cross-validated elastic-net and random forest modelling, along with a pragmatic ratio detection procedure. Results Disease-specific transcriptomes were defined in IBD [8697 transcripts], CD [7152], and UC [8521], with the most highly significant changes in single genes, including CD177 (log(2)-fold change [LFC] = 4.63, p = 4.05 x 10(-118)), MCEMP1 [LFC = 2.45, p = 7.37 x 10(-109)], and S100A12 [LFC = 2.31, p = 2.15 x 10(-93)]. Significantly over-represented pathways included IL-1 [p = 1.58 x 10(-11)], IL-4, and IL-13 [p = 8.96 x 10(-9)]. Highly concordant results were obtained using multiple regulatory activity inference tools applied to the discovery and replication cohorts. These analyses demonstrated central roles in IBD for the transcription factors NFE2, SPI1 [PU.1], CEBPB, and IRF2, all regulators of cytokine signalling, based on a consistent signal across cohorts and transcription factor ranking methods. A number of simple transcriptome-based models were associated with the need for treatment escalation, including the binary CLEC5A/CDH2 expression ratio in UC (hazard ratio = 23.4, 95% confidence interval [CI] 5.3-102.0). Conclusions Transcriptomic analysis has allowed for a detailed characterisation of IBD pathobiology, with important potential translational implications.

Background and Aims: Patient-reported outcome measures [PROMs] aim to measure patients perception of how their disorder influences everyday functioning. The objective of this study was to develop a PROM to assess disease activity in microscopic colitis [MC] fulfilling the requirements of the Food and Drug Administration [FDA].

Methods: The European Microscopic Colitis Activity Index [E-MCAT] was developed in four steps. [1] A list of symptoms associated with active MC was created by a group of experts in the field. [2] Content validity of the symptoms was performed by experts [n= 14] and patients [n = 79] using the Content Validity Index. [3] Questions and response alternatives were created for each symptom, and validity of the E-MCAI was evaluated with cognitive interviews with patients [n= 7] and by the experts. [4] A pilot postal survey was performed to ensure usability.

Results: Seven of the symptoms related to active MC fulfilled the criteria for content validity and were included in the E-MCAI: stool consistency, stool frequency, stools at night, feel a need to pass more stools shortly after a bowel movement, urgent need to empty the bowel, leakage of stool and abdominal pain.The development and validation process resulted in the current version of the E-MCAI consisting of six questions related to MC. Conclusions: The E-MCAI was developed using the methods advocated by the FDA.The evaluation indicates good content validity. Further evaluation will be performed to achieve construct validity, reliability and responsiveness in future cross-sectional and longitudinal studies.

Background Evidence for second-line therapy in patients with microscopic colitis [MC] failing budesonide is scarce, although anti-tumour necrosis factors [anti-TNFs], methotrexate and azathioprine have been reported to be effective in small cohort studies. Vedolizumab, a monoclonal antibody targeting 47-integrin, prevents homing of T-cells to the gut. We evaluated clinical remission with vedolizumab in budesonide-refractory MC patients. Methods We solicited gastroenterologists in Europe and Canada for cases of MC treated with vedolizumab. Vedolizumab 300 mg IV was administered at weeks 0, 2 and 6, and then every 8 weeks. Clinical remission and histological remission were defined as less than three stools per day and normalization of histology, respectively, after induction treatment. Results Eleven cases were retrieved (nine females, lymphocytic colitis [LC] n = 5, collagenous colitis [CC] n = 6). Median [interquartile range] disease duration at vedolizumab initiation was 51 [29-70] months. Nine of 11 patients had failed one immunosuppressant and ten of 11 at least one anti-TNF agent. After three infusions of vedolizumab, clinical remission was observed in 5/11 patients [two LC and three CC] of whom three remained well with maintenance therapy [median duration of 13 months]. Biopsies were obtained from 9/11 patients. Histological remission was observed in 3/4 patients with clinical remission [2/3 CC, 1/1 LC] and 0/5 patients without clinical improvement. Conclusion In a series of highly refractory MC patients, vedolizumab induced clinical remission in 5/11 subjects, of whom 75% showed normalized histology. Larger randomized trials are needed to assess the efficacy of vedolizumab in patients with MC.

Epidemiological studies demonstrate an increased risk of colorectal cancer in patients with inflammatory bowel disease (IBD). A detailed literature review was conducted on epidemiology, risk factors, pathophysiology, chemoprevention and outcomes of colorectal cancer (CRC) in IBD as part of the 3rd ECCO scientific pathogenesis workshop.

Objectives To examine the association between early-life smoking exposure and later risk of inflammatory bowel disease [IBD].Methods We followed 115663 participants from the Norwegian Mother, Father and Child [MoBa] and All Babies in Southeast Sweden [ABIS] cohorts from birth [1997-2009] through 2021. IBD was identified through national patient registers. Validated questionnaire data defined maternal smoking during pregnancy, maternal environmental tobacco smoke [ETS] exposure during pregnancy, and child ETS exposure by ages 12 and 36 months. Cox regression was used to estimate adjusted hazard ratios [aHRs] for sex, maternal age, education level, parental IBD, and origin. Cohort-specific estimates were pooled using a random-effects model.Results During 1 987 430 person-years of follow-up, 444 participants developed IBD [ABIS, 112; MoBa, 332]. Any vs no maternal smoking during pregnancy yielded a pooled aHR of 1.30 [95% CI = 0.97-1.74] for offspring IBD. Higher level of maternal smoking during pregnancy (compared with no smoking, average &gt;= 6 cigarettes/day: pooled aHR = 1.60 [95% CI = 1.08-2.38]) was associated with offspring IBD, whereas a lower smoking level was not (average 1-5 cigarettes/day: pooled aHR = 1.09 [95% CI = 0.73-1.64]). Child ETS exposure in the first year of life was associated with later IBD (any vs no ETS, pooled aHR = 1.32 [95% CI = 1.03-1.69]). Estimates observed for child ETS exposure by 36 months were similar but not statistically significant.Conclusions In this prospective Scandinavian cohort study, children exposed to higher levels of maternal smoking during pregnancy or ETS during the first year of life were at increased risk of later IBD.

Background and Aims: The disease course of microscopic colitis [MC] is considered chronic but benign. However, this assumption is based on mainly retrospective studies, reporting on incomplete follow-up of selective cohorts. Systematic, prospective and unbiased data to inform patients and healthcare professionals on the expected course of the disease and real-life response to therapy are warranted.

Methods: A prospective, pan-European, multi-centre, web-based registry was established. Incident cases of MC were included. Data on patient characteristics, symptoms, treatment and quality of life were systematically registered at baseline and during real-time follow-up. Four disease course phenotypes were discriminated and described.

Results: Among 381 cases with complete 1-year follow-up, 49% had a chronic active or relapsing disease course, 40% achieved sustained remission after treatment and 11% had a quiescent course. In general, symptoms and quality of life improved after 3 months of follow-up. A relapsing or chronic active disease course was associated with significantly more symptoms and impaired quality of life after 1 year.

Conclusions: A minority of MC patients follow a quiescent disease course with spontaneous clinical improvement, whereas the majority suffer a chronic active or relapsing disease course during the first year after diagnosis, with persisting symptoms accompanied by a significantly impaired quality of life.

Background and aims: The thiopurines are widely used in the treatment of inflammatory bowel disease, but are limited by poor dose effect relationship. The objective was to assess the ability of a novel assay, determining the mono-, di-, and triphosphates, of thioguanine as well as methylthioinosine as individual metabolites in erythrocytes, to predict clinical outcome compared to a routine assay, determining metabolites as sums. Methods: Samples from 79 patients with Crohns disease or ulcerative colitis treated with azathioprine or mercaptopurine were analysed by both assays. Clinical status was determined by the Harvey-Bradshaw and Walmsley indices. The genotypes of thiopurine methyltransferase (TPMT) and inosine triphosphatase were determined. Results: TPMT wild-type patients with thioguanine nucleotide (TGN) levels below the cut-off level were more likely to have active disease when TGN was measured by the novel assay (p = 0.02), and when thioguanosine triphosphate (TGTP) was measured separately (p = 0.01). When TGN was measured by the routine assay the correlation was not evident (p = 0.12). Neither TGN levels nor TGTP correlated to disease activity in TPMT deficient patients. Patients with methyl thioinosine nucleotide (meTIN) levels above 1500 pmol/8 x 10less than^greater than8 RBCs were more likely to have active disease (p = 0.07). We observed good correlations between the mono-, di-, and triphosphates and their respective sums (R-2 greater than 0.88). Conclusions: The novel TGN assay was better in predicting clinical outcome compared to the routine assay, while determination of TGTP had no clinical advantage and TGTP ratio was not correlated to disease activity. (C) 2014 European Crohns and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

Background and Aims: Epidemiological studies suggest an increasing global incidence of microscopic colitis, including collagenous colitis and lymphocytic colitis. We aimed to investigate the incidence and prevalence of microscopic colitis in Denmark. Methods: In a nationwide cohort study, we included all incident patients with a recorded diagnosis of collagenous colitis or lymphocytic colitis in the Danish Pathology Register between 2001 and 2016. Results: A total of 14 302 patients with microscopic colitis-8437 [59%] with collagenous and 5865 [41%] with lymphocytic colitis-were identified during the study period. The prevalence in December 2016 was estimated to be 197.9 cases per 100 000 inhabitants. Microscopic colitis was more prevalent among females (n = 10 127 [71%]), with a mean annual incidence of 28.8, compared with 12.3 per 100 000 person-years among males. The overall mean incidence during the study period was 20.7 per 100 000 person-years. Mean age at time of diagnosis was 65 years (standard deviation [SD]:14) for microscopic colitis, 67 [SD:13] for collagenous colitis, and 63 [SD:15] for lymphocytic colitis. The overall incidence increased significantly from 2.3 cases in 2001 to 24.3 cases per 100 000 person-years in 2016. However, the highest observed incidence of microscopic colitis was 32.3 cases per 100 000 person-years in 2011. Large regional differences were found, with the highest incidence observed in the least populated region. Conclusions: The incidence of microscopic colitis in Denmark has increased 10-fold during the past 15 years and has now surpassed that of Crohns disease and ulcerative colitis. However, incidence has stabilised since 2012, suggesting that a plateau has been reached.

Background and Aims: The disease course of microscopic colitis [MC], encompassing collagenous colitis [CC] and lymphocytic colitis [LC], is not well known. In a Danish nationwide cohort, we evaluated the disease activity patterns as well as the risk of colorectal cancer [CRC] and mortality based on disease severity. Methods: All incident MC patients [n = 14 302] with a recorded diagnosis of CC [n = 8437] or LC [n = 5865] in the Danish Pathology Register, entered between 2001 and 2016, were matched to 10 reference individuals [n = 142 481]. Incident cases of CRC after the index date were captured from the Danish Cancer Registry. Mortality data were ascertained from the Danish Registry of Causes of Death, and information about treatment was obtained from the Danish National Prescription Registry. The risk of CRC and mortality analyses were investigated by Cox regression and Kaplan-Meier estimates. Results: We identified a self-limiting or transient disease course in 70.6% of LC patients and in 59.9% of CC patients, p&lt;0.001. Less than 5% of MC patients experienced a budesonide-refractory disease course and were treated with immunomodulators or biologic treatment. A total of 2926 [20.5%] MC patients and 24 632 [17.3%] reference individuals died during the study period. MC patients with a severe disease had a relative risk [RR] of mortality of 1.41 (95% confidence interval [CI]: 1.32-1.50) compared with reference individuals. Only 90 MC patients were diagnosed with CRC during follow-up, corresponding to an RR of 0.48 [95% CI: 0.39-0.60]. Conclusions: A majority of MC patients experience an indolent disease course with a lower risk of developing CRC compared with the background population.

Objective

Microscopic colitis [MC], encompassing collagenous colitis [CC] and lymphocytic colitis [LC], is an increasingly prevalent gastrointestinal disease with an unknown aetiology. Previous research has reported significant differences in the incidence of MC within Denmark, with the lowest incidence found in the most populated region [Capital Region of Denmark]. Our aim was to elucidate the causes of these regional differences.

Design

All incident MC patients [n = 14 302] with a recorded diagnosis of CC [n = 8437] or LC [n = 5865] entered in The Danish Pathology Register between 2001 and 2016 were matched to 10 reference individuals [n = 142 481]. Information regarding drug exposure, including proton pump inhibitors [PPIs], selective serotonin reuptake inhibitors [SSRIs], statins, and nonsteroidal anti-inflammatory drugs [NSAIDs], were retrieved from The Danish National Prescription Registry. Information regarding endoscopy rate, smoking-related diseases, and immune-mediated inflammatory diseases were acquired from The Danish National Patient Registry.

Results

Smoking, immune-mediated inflammatory diseases, exposure to PPIs, SSRIs, statins, and NSAIDs were significantly associated with MC in all Danish regions. The association between drug exposure and MC was weakest in the Capital Region of Denmark with an odds ratio of 1.8 (95% confidence interval [CI]: 1.61-2.01). The relative risk of undergoing a colonoscopy with biopsy was significantly increased in sex- and age-matched controls in all regions compared with controls from the Capital Region of Denmark, with the greatest risk found in the Region of Southern Denmark, 1.37 [95% CI: 1.26-1.50].

Conclusions

The cause of the regional differences in MC incidence in Denmark seems to be multifactorial, including variations in disease awareness and distribution of risk factors.

Background

Whereas the exact aetiology of microscopic colitis [MC] remains unknown, a dysregulated immune response to luminal factors or medications is the most accepted pathogenesis hypothesis.

Methods

We conducted a systematic review of the pathogenesis of MC. We applied the Joanna Briggs Institute methodologies and the PRISMA statement for the reporting of systematic reviews [PROSPERO Trial Identifier: CRD42020145008]. Populations, Exposure of interest, and Outcome [PEO] questions were used to explore the following topics in MC: 1] intestinal luminal factors; 2] autoimmunity; 3] innate immunity; 4] adaptive immunity; 5] extracellular matrix; 6] genetic risk factors; and 7] mechanism of diarrhoea. A search was done in PubMed, Embase, and Web of Science up to February 2020. A narrative description was performed explaining the findings for each aspect of MC aetiopathogenesis.

Results

Thirty-eight documents provided evidence for PEO1, 100 for PEO2, 72 for PEO3 and 4, 38 for PEO5, 20 for PEO6, and 23 for PEO7. The majority of documents were cohorts, case reports, and case series, with a few case-control and some experimental studies. Consistency among data provided by different studies was considered to support pathogenetic hypotheses. MC is a multifactorial disease believed to involve innate and adaptive immune responses to luminal factors, genetic risk, autoimmunity, and extracellular matrix alterations, all contributing by varied mechanisms to watery diarrhoea.

Conclusions

This is the first systematic review on the aetiology of MC supporting the notion that MC is a multifactorial disease. However, high-profile studies are lacking, and most evidence derives from small heterogeneous studies.

Background and Aims: Microscopic colitis [MC] is currently regarded as an inflammatory bowel disease that manifests as two subtypes: collagenous colitis [CC] and lymphocytic colitis [LC]. Whether these represent a clinical continuum or distinct entities is, however, an open question. Genetic investigations may contribute important insight into their respective pathophysiologies.Methods: We conducted a genome-wide association study [GWAS] meta-analysis in 1498 CC, 373 LC patients, and 13 487 controls from Europe and the USA, combined with publicly available MC GWAS data from UK Biobank and FinnGen [2599 MC cases and 552 343 controls in total]. Human leukocyte antigen [HLA] alleles and polymorphic residues were imputed and tested for association, including conditional analyses for the identification of key causative variants and residues. Genetic correlations with other traits and diagnoses were also studied.Results: We detected strong HLA association with CC, and conditional analyses highlighted the DRB1*03:01 allele and its residues Y26, N77, and R74 as key to this association (best p = 1.4 x 10(-23), odds ratio [OR] = 1.96). Nominally significant genetic correlations were detected between CC and pneumonia [r(g) = 0.77; p = 0.048] and oesophageal diseases [r(g) = 0.45, p = 0.023]. An additional locus was identified in MC GWAS analyses near the CLEC16A and RMI2 genes on chromosome 16 [rs35099084, p = 2.0 x 10(-8), OR = 1.31]. No significant association was detected for LC.Conclusion: Our results suggest CC and LC have distinct pathophysiological underpinnings, characterised by an HLA predisposing role only in CC. This challenges existing classifications, eventually calling for a re-evaluation of the utility of MC umbrella definitions.