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Aims: To review studies examining the appendiceal microbiota and microbial changes in acute appendicitis. Methods: After a systematic literature search, 11 studies examining the appendiceal microbiota (414 samples) using non-culture-based methods were included. Results: The appendiceal microbiota showed decreased α-diversity compared with fecal microbiota. Inflamed and uninflamed appendices showed differences in β-diversity, and there was an increased abundance of oral-associated bacteria in inflamed versus uninflamed appendices. Conclusion: The appendiceal microbiota exhibits lower α-diversity than the fecal microbiota, with an increased abundance of oral-associated bacteria. Compared with uninflamed appendices, the appendix microbiota in acute appendicitis also showed increased abundance of oral-associated bacteria, but no bacterial profile unique to either complicated or uncomplicated appendicitis was found. Aims: To review studies examining the appendiceal microbiota and microbial changes in acute appendicitis. Methods: After a systematic literature search, 11 studies examining the appendiceal microbiota (414 samples) using non-culture-based methods were included. Results: The appendiceal microbiota showed decreased α-diversity compared with fecal microbiota. Inflamed and uninflamed appendices showed differences in β-diversity, and there was an increased abundance of oral-associated bacteria in inflamed versus uninflamed appendices. Conclusion: The appendiceal microbiota exhibits lower α-diversity than the fecal microbiota, with an increased abundance of oral-associated bacteria. Compared with uninflamed appendices, the appendix microbiota in acute appendicitis also showed increased abundance of oral-associated bacteria, but no bacterial profile unique to either complicated or uncomplicated appendicitis was found. Plain language summary: This article represents a summary of the current literature examining the bacteria in the human appendix.We aimed to describe the bacterial community in the appendix and look for evidence of bacterial differences between diseased and healthy appendices, as well as evidence of bacteria being the cause of acute appendicitis. We found that the bacteria in the appendix are different from the bacteria in stool. Furthermore, bacteria are different when comparing diseased and healthy appendices. The diseased appendix had more types of bacteria that are normally found in the mouth than the healthy appendix. Our summary did not find any evidence that bacteria are the main cause of developing acute appendicitis. Tweetable abstract: This review found a lower ?-diversity of the appendiceal microbiota compared with the fecal microbiota and an increased presence of bacteria commonly found in the oral cavity in the appendix. Acute appendicitis is characterized by an altered microbiota with increased abundance of Fusobacteria.

Introduction: Biologic therapy is widely used for inflammatory bowel disease (IBD) and may decrease surgery rates. However, it remains uncertain if there is unwarranted geographic variation in access to biologic therapy. The aim of the study was to explore if all patients had equal access to biologic therapy in the North Denmark Region.Methods: A cross-sectional register-based study of use of biologics, hospital contacts and surgery among all IBD patients having a hospital contact in the geographically well-defined North Denmark Region during 2016-2018. ICD-10 diagnosis codes, hospital contacts and procedure codes were retrieved from the region's hospital registry. The population is served by an Academic Hospital and two Non-Academic Hospitals constituting three referral areas (according to postal codes).Results: In total, 2371 patients with ulcerative colitis (UC) and 1383 patients with Crohn's disease (CD) had a hospital contact in the region during 2016-2018. Compared to patients from the Academic Hospital, patients from the Non-Academic Hospitals experienced a lower incidence of biologic therapy for UC IRR 0.786 (0.621: 0.994), as well as for CD IRR 0.912 (0.781: 1.065). The incidence of bowel related hospital contacts were higher in patients from Non-Academic hospitals for both UC IRR 1.318 (1.207: 1.438) and CD IRR 1.165 (0.915: 1.483).Conclusions: Patients with IBD living in a referral area to a Non-Academic Hospital in the North Denmark Region are less likely to receive biologics. This was associated with an increased prevalence of IBD related surgical procedures. Introduction: Biologic therapy is widely used for inflammatory bowel disease (IBD) and may decrease surgery rates. However, it remains uncertain if there is unwarranted geographic variation in access to biologic therapy. The aim of the study was to explore if all patients had equal access to biologic therapy in the North Denmark Region.Methods: A cross-sectional register-based study of use of biologics, hospital contacts and surgery among all IBD patients having a hospital contact in the geographically well-defined North Denmark Region during 2016-2018. ICD-10 diagnosis codes, hospital contacts and procedure codes were retrieved from the region's hospital registry. The population is served by an Academic Hospital and two Non-Academic Hospitals constituting three referral areas (according to postal codes).Results: In total, 2371 patients with ulcerative colitis (UC) and 1383 patients with Crohn's disease (CD) had a hospital contact in the region during 2016-2018. Compared to patients from the Academic Hospital, patients from the Non-Academic Hospitals experienced a lower incidence of biologic therapy for UC IRR 0.786 (0.621: 0.994), as well as for CD IRR 0.912 (0.781: 1.065). The incidence of bowel related hospital contacts were higher in patients from Non-Academic hospitals for both UC IRR 1.318 (1.207: 1.438) and CD IRR 1.165 (0.915: 1.483).Conclusions: Patients with IBD living in a referral area to a Non-Academic Hospital in the North Denmark Region are less likely to receive biologics. This was associated with an increased prevalence of IBD related surgical procedures.

BackgroundInflammatory bowel disease (IBD) is associated with psychiatric diseases, but it is unclear to what degree patients with IBD are affected over their lifetime. We aimed to longitudinally investigate the risk of anxiety, depression, and bipolar disorder before and after IBD diagnosis to understand the full burden of these diseases in patients with IBD.MethodsIn this population based cohort study, we identified 22,103 patients diagnosed with IBD between January 1, 2003 and December 31, 2013 in the Danish National registers and 110,515 matched reference individuals from the general population. We calculated yearly prevalence of hospital contacts for anxiety, depression, and bipolar disorder and dispensed prescriptions for antidepressants from five years before to ten years after IBD diagnosis. We used logistic regression to calculate prevalence odds ratios (OR) for each outcome prior to IBD diagnosis, and Cox regression to calculate hazard ratios (HR) of new outcomes after IBD diagnosis.FindingsDuring >150,000 person years follow-up, patients with IBD had higher risk of anxiety (OR 1.4; 95% confidence interval (CI) 1.2–1.7) and depression (OR 1.4; 95% CI 1.3–1.6) starting at least five years before and continuing until at least ten years after IBD diagnosis (HR 1.3; 95% CI 1.1–1.5 for anxiety and HR 1.5; 95% CI 1.4–1.7 for depression). The risk was particularly high around IBD diagnosis and in patients diagnosed with IBD after the age of 40 years. We found no association between IBD and bipolar disorder.InterpretationThis population-based study suggests that anxiety and depression are clinically significant comorbidities of IBD both before and after IBD diagnosis, which warrant thorough evaluation and management, particularly around the time of IBD diagnosis. BackgroundInflammatory bowel disease (IBD) is associated with psychiatric diseases, but it is unclear to what degree patients with IBD are affected over their lifetime. We aimed to longitudinally investigate the risk of anxiety, depression, and bipolar disorder before and after IBD diagnosis to understand the full burden of these diseases in patients with IBD.MethodsIn this population based cohort study, we identified 22,103 patients diagnosed with IBD between January 1, 2003 and December 31, 2013 in the Danish National registers and 110,515 matched reference individuals from the general population. We calculated yearly prevalence of hospital contacts for anxiety, depression, and bipolar disorder and dispensed prescriptions for antidepressants from five years before to ten years after IBD diagnosis. We used logistic regression to calculate prevalence odds ratios (OR) for each outcome prior to IBD diagnosis, and Cox regression to calculate hazard ratios (HR) of new outcomes after IBD diagnosis.FindingsDuring >150,000 person years follow-up, patients with IBD had higher risk of anxiety (OR 1.4; 95% confidence interval (CI) 1.2–1.7) and depression (OR 1.4; 95% CI 1.3–1.6) starting at least five years before and continuing until at least ten years after IBD diagnosis (HR 1.3; 95% CI 1.1–1.5 for anxiety and HR 1.5; 95% CI 1.4–1.7 for depression). The risk was particularly high around IBD diagnosis and in patients diagnosed with IBD after the age of 40 years. We found no association between IBD and bipolar disorder.InterpretationThis population-based study suggests that anxiety and depression are clinically significant comorbidities of IBD both before and after IBD diagnosis, which warrant thorough evaluation and management, particularly around the time of IBD diagnosis.

Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, is a chronic, relapsing immune-mediated disease with a varying and sometimes severe disease course. IBD is often diagnosed in early adulthood and can lead to a substantial decline in quality of life. It has been suggested that patients with IBD are at increased risk of depression and anxiety, but it is still unclear to what extent these diseases co-occur and in what sequence they arise. This Review summarizes the literature on the degree of co-occurrence of IBD with depression and anxiety and the temporal relationship between these diseases. We also discuss the effect of psychological stress on the onset and course of IBD. In addition, we outline the possible mechanisms underlying the co-occurrence of IBD and depression and anxiety, which include changes in brain signalling and morphology, increases in peripheral and intracerebral pro-inflammatory cytokines, impairment of the nitric oxide pathway, changes in vagal nerve signalling, gut dysbiosis and genetics. Finally, we examine the possible effects of treatment of depression and anxiety on the risk and course of IBD, the influence of psychological interventions on IBD, and the effects of IBD treatment on psychiatric comorbidity.

Aim: Patients with Crohn's disease (CD) often suffer from perianal fistulizing disease. Their risk of anorectal cancer remains uncertain. We aimed to examine the long-term risk of anorectal cancer in a population-based cohort of CD patients with anorectal fistula.Method: Our study population covered all individuals (n = 7 987 520) aged 15+ years living in Denmark from 1978 to 2018. We identified all patients with CD and anorectal fistula in the Danish National Patient Register (NPR) and 50 matched noninflammatory bowel disease (IBD) individuals from the general population. Using Cox regression analyses, we examined the risk of anorectal cancer in CD fistula patients versus non-IBD individuals. All patients with CD were identified using codes from the International Classification of Diseases and their data extracted from the NPR. The main outcome measure was cases of anorectal cancer.Results: A total of 2786 CD patients with anorectal fistula and 139 300 non-IBD individuals were followed for 1 553 917 person-years. During follow-up, anorectal cancer was observed in 19 CD patients (0.68%) and 340 non-IBD individuals (0.24%), corresponding to a 2.9-fold increased hazard ratio (HR) of anorectal cancer in CD fistula patients (95% CI 1.80-4.53), with a particularly high risk of anal cancer (HR 15.13, 95% CI 6.88-33.31) and a mean time from CD fistula diagnosis to anorectal cancer of 6.7 (SD 6.5) years. The risk was slightly higher in women than men and had no apparent relation to treatment with tumour necrosis factor-α inhibitors. Sensitivity analyses using CD nonfistula patients for comparison revealed similar results. Individual data on smoking and infection with human papilloma virus were not available.Conclusion: Patients with CD and anorectal fistula have a three-fold increased risk of anorectal cancer compared with the general population. The number needed to surveil to detect one case of anorectal cancer in this patient population was 2160 patients per year in patients with long-standing fistula (>6 years). Aim: Patients with Crohn's disease (CD) often suffer from perianal fistulizing disease. Their risk of anorectal cancer remains uncertain. We aimed to examine the long-term risk of anorectal cancer in a population-based cohort of CD patients with anorectal fistula.Method: Our study population covered all individuals (n = 7 987 520) aged 15+ years living in Denmark from 1978 to 2018. We identified all patients with CD and anorectal fistula in the Danish National Patient Register (NPR) and 50 matched noninflammatory bowel disease (IBD) individuals from the general population. Using Cox regression analyses, we examined the risk of anorectal cancer in CD fistula patients versus non-IBD individuals. All patients with CD were identified using codes from the International Classification of Diseases and their data extracted from the NPR. The main outcome measure was cases of anorectal cancer.Results: A total of 2786 CD patients with anorectal fistula and 139 300 non-IBD individuals were followed for 1 553 917 person-years. During follow-up, anorectal cancer was observed in 19 CD patients (0.68%) and 340 non-IBD individuals (0.24%), corresponding to a 2.9-fold increased hazard ratio (HR) of anorectal cancer in CD fistula patients (95% CI 1.80-4.53), with a particularly high risk of anal cancer (HR 15.13, 95% CI 6.88-33.31) and a mean time from CD fistula diagnosis to anorectal cancer of 6.7 (SD 6.5) years. The risk was slightly higher in women than men and had no apparent relation to treatment with tumour necrosis factor-α inhibitors. Sensitivity analyses using CD nonfistula patients for comparison revealed similar results. Individual data on smoking and infection with human papilloma virus were not available.Conclusion: Patients with CD and anorectal fistula have a three-fold increased risk of anorectal cancer compared with the general population. The number needed to surveil to detect one case of anorectal cancer in this patient population was 2160 patients per year in patients with long-standing fistula (>6 years).

The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant. The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant.

BackgroundThere is an increasing incidence of inflammatory bowel disease (IBD) for which environmental factors are suspected. Antibiotics have been associated with development of IBD in earlier generations, but their influence on IBD risk in adults is uncertain.ObjectiveTo assess the impact of antibiotic exposure, including dose–response, timing and antibiotic class, on the risk of IBD in all individuals aged ≥10 years.DesignUsing Denmark nationwide registries, a population-based cohort of residents aged ≥10 years was established between 2000 and 2018. Incidence rate ratios (IRRs) for IBD following antibiotic exposure were calculated using Poisson regression.ResultsThere were a total of 6 104 245 individuals, resulting in 87 112 328 person-years of follow-up, and 52 898 new cases of IBD. Antibiotic exposure was associated with an increased risk of IBD as compared with no antibiotic exposure for all age groups, although was greatest among individuals aged 40–60 years and ≥60 years (age 10–40 years, IRR 1.28, 95% CI 1.25 to 1.32; age 40–60 years, IRR 1.48, 95% CI 1.43 to 1.54; age ≥60 years, IRR 1.47, 95% CI 1.42 to 1.53). For all age groups a positive dose–response was observed, with similar results seen for both ulcerative colitis and Crohn’s disease. The highest risk of developing IBD was seen 1–2 years after antibiotic exposure, and after use of antibiotic classes often prescribed to treat gastrointestinal pathogens.ConclusionAntibiotic exposure is associated with an increased risk of IBD, and was highest among individuals aged 40 years and older. This risk increased with cumulative antibiotic exposure, with antibiotics targeting gastrointestinal pathogens and within 1–2 years after antibiotic exposure.

INTRODUCTION: While the incidence of inflammatory bowel disease (IBD) is rising globally, it has been suggested to stabilize in westernized countries, but this has not yet been shown in exhaustive and large cohorts. We generated an IBD cohort in North Denmark (NorDIBD) of 6,158 patients with IBD diagnosed from 1978 to 2020, based on all recorded and verified IBD diagnoses in the region. While describing the establishment of this cohort, we aimed to present the accurate incidence and prevalence of IBD over 4 decades.METHODS: The NorDIBD cohort covered all pediatric and adult patients with an IBD diagnosis dated between January 1, 1978, and December 31, 2020, and living in North Denmark, hence forming an unselected population-based patient cohort. IBD incidence rates between 1978 and 2020 and IBD point prevalences between 2003 and 2020 were calculated.RESULTS: We observed a 4-fold increase in the incidence of IBD from 11.5 per 100,000 persons (95% confidence interval [CI] 8.4-14.6) in the year 1978 to 51.3/100,000 (95% CI 45.5-57.1) in the year 2014, whereas in 2020, this rate stabilized. The overall prevalence of IBD more than doubled from 2003 to 2020, from 424 (95% CI 407-443) in 2003 to 872 (95% CI 849-896) IBD cases per 100,000 persons in 2020.DISCUSSION: Our population-based NorDIBD cohort suggests stabilizing of the incidence of IBD in Denmark, whereas the prevalence continues to rise. Because the data represent a 10% sample of the entire Danish IBD population, we believe that data can be extrapolated to the IBD population in general and used for healthcare planning.

BACKGROUND: Escalation to anti-tumour necrosis factor (anti-TNF) in inflammatory bowel disease (IBD) patients on thiopurine is a common clinical scenario. However, the impact of discontinuing thiopurine at escalation is unclear.AIM: To assess the impact of discontinuing versus continuing thiopurine therapy at anti-TNF initiation.METHODS: We used the Danish registries to establish a national cohort of patients with IBD on thiopurine therapy prior to initiating anti-TNF from 2003 to 2018. We compared patients discontinuing thiopurine therapy within 90 days of anti-TNF initiation to those continuing. Our primary outcome was a composite of any new oral corticosteroid use, IBD-related hospitalization, surgery or death. We used Cox regression models to calculate adjusted hazard ratios (aHR) and 95% confidence intervals (CI).RESULTS: Of the 10,352 anti-TNF exposed patients, 2,630 (1590 Crohn's disease (CD) and 1040 ulcerative colitis (UC)) received thiopurines prior to anti-TNF. After anti-TNF initiation, 979 patients discontinued thiopurines. Discontinuing thiopurines within 90 days of anti-TNF initiation, increased the risk of the primary outcome (aHR: 1.22; 95% CI: 1.10-1.36), particularly for IBD-related hospitalization (aHR: 1.14; 95% CI: 1.00-1.31) and oral corticosteroid use (aHR: 1.27; 95% CI: 1.13-1.44). This increased risk of the primary outcome was seen in both CD (aHR: 1.17; 95% CI 1.02-1.34) and UC (aHR: 1.32; 95% CI: 1.12-1.55).CONCLUSIONS: In a nationwide cohort study of IBD patients, we observed that discontinuing thiopurines after anti-TNF initiation was associated with an increased risk of adverse outcomes, in particular an increase in hospitalizations. Further interventional studies exploring this common clinical scenario are required.

Objectives: This is a protocol for a Cochrane Review (prognosis). The objectives are as follows:. Primary objectives The primary objectives are to identify, describe, and appraise all prognostic models developed to predict colorectal cancer incidence or mortality in patients with IBD, at any time point after the clinical diagnosis of IBD, and if possible meta-analyse their predictive performances. Investigation of sources of heterogeneity between studies Sources of heterogeneity to be investigated comprise differences in the definition of colorectal dysplasia, colorectal cancer and IBD, the type of IBD investigated, study design, time point for prognostication after the clinical diagnosis of IBD, time horizon for outcome measurements, length of follow-up, and statistical analysis applied (Debray 2017).

Background & Aims: Patients with inflammatory bowel disease (IBD) are at increased risk of acute arterial events. Treatment with anti–tumor necrosis factor (anti-TNF) agents has been associated with a protective effect against the first occurrence of acute arterial events, but the impact of treatment with anti-TNF in patients with a previous history of acute arterial events remains unclear. We assessed the effect of anti-TNF and thiopurines on the risk of recurrent acute arterial events in patients with IBD in a nationwide cohort. Methods: Based on the French nationwide health insurance database, patients with IBD and a previous history of an acute arterial event were followed up from January 1, 2009, until December 31, 2018. The risk of acute arterial event recurrence associated with anti-TNF and thiopurine exposure was assessed using marginal structural Cox proportional hazard models adjusted for baseline and time-varying covariates. Results: A total of 27,185 patients were included. During 121,822 person-years (median follow-up period, 4.0 y), 6865 recurrent acute arterial events occurred (incidence rate per 1000 person-years, 56.4; 95% CI, 55.0–57.7). Exposure to both anti-TNF and thiopurines were associated with a decreased risk of recurrent acute arterial events compared with the absence of exposure to either treatment (hazard ratio, 0.75; 95% CI, 0.63–0.90 and hazard ratio, 0.76; 95% CI, 0.66–0.88, respectively). Conclusions: In a nationwide cohort study of patients with IBD and a previous history of an acute arterial event, exposure to both anti-TNF and thiopurines were associated with a decreased risk of recurrent acute arterial events.

BACKGROUND & AIMS: Current knowledge regarding the epidemiology of pouchitis is based on highly selected, mostly single-center, patient cohorts. Our objective was to prospectively determine the population-based incidence of pouchitis in patients with ulcerative colitis in the first 2 years after ileal pouch-anal anastomosis and analyze time trends of the incidence of pouchitis.METHODS: Using national registries, we established a population-based cohort of all Danish patients undergoing proctocolectomy with ileal pouch-anal anastomosis for ulcerative colitis between 1996 and 2018. The primary outcome was the development of pouchitis within the first 2 years after surgery, evaluated by time period. We used Kaplan-Meier and Cox proportional hazard modeling to evaluate the time to development of pouchitis.RESULTS: Overall, 1664 patients underwent an ileal pouch-anal anastomosis. The cumulative incidence of pouchitis in the 2 years after ileal pouch-anal anastomosis increased throughout the study period, from 40% in the period from 1996 to 2000 (95% CI, 35%-46%) to 55% in the period from 2015 to 2018 (95% CI, 48%-63%). Patients undergoing surgery between 2015 and 2018 also showed an increased risk of pouchitis compared with the earliest study period (1996-2000) after adjusting for sex, age, and socioeconomic status (hazard ratio, 1.57; 95% CI, 1.20-2.05).CONCLUSIONS: This population-based study showed a 15% absolute and 38% relative increase in the incidence of pouchitis among patients undergoing surgery between 1996 and 2018, with the greatest cumulative incidence of pouchitis shown in the most recent era (2015-2018). The striking increase in the incidence of pouchitis highlights the need for further research into causes and prevention of pouchitis.

The epidemiology of inflammatory bowel disease (IBD) has undergone considerable shifts since its emergence in the Western world over a century ago, especially in the last few decades, with increasing global burden of disease. IBD incidence continues to rise in developed countries in all age groups which is contributing to compounding prevalence. Further, IBD incidence is rising sharply in Asia and other recently developed and developing countries. In this review, we discuss the implications of changing trends of IBD epidemiology. First, changing patterns provide insights into IBD causes, as they occur concurrent with shifts in the environment, cultures, and attitudes. Understanding the impact of the environment on IBD risk can help towards prediction and prevention strategies. Second, we must prepare healthcare systems for the rising burden of IBD and address it at various levels towards improving outcomes and health, overall.

Background: The association between autoimmune diseases and microscopic colitis remains uncertain. Aims: To describe the association between autoimmune diseases and microscopic colitis by using a matched case–control design based on nationwide registry data. Methods: All adult Danish patients with a diagnosis of microscopic colitis from 2001 to 2018 were identified from nationwide registries. Odds of autoimmune diseases were compared between cases with microscopic colitis and sex- and age-matched controls from the background population in a 1:10 ratio and evaluated by logistic regression calculating odds ratios (OR) with 95% confidence intervals (CI) adjusted for comorbidity. Analyses were stratified according to sex, age and the subtypes of lymphocytic and collagenous colitis. Results: We identified 15 597 cases with microscopic colitis and matched to 155 910 controls. In total, 3491 (22%) of patients with microscopic colitis had concomitant autoimmune disease compared to 16 521 (11%) of controls (OR, 2.46; 95% CI, 2.36-2.56). Adjusting for comorbidities reduced the OR to 2.09 (95% CI, 2.01-2.19). Analyses showed increased ORs with 16 different autoimmune diseases, particularly of gastrointestinal and endocrine origin, and connective tissue disorders. The highest ORs were for coeliac disease (OR = 10.15; 95% CI, 8.20-12.6), Crohn’s disease (OR = 2.47; 95% CI, 2.10-2.91) and ulcerative colitis (OR = 6.73; 95% CI, 6.20-7.30). In stratified analyses younger age at diagnosis and collagenous colitis were associated with higher odds. Conclusion: Using nationwide registry data, microscopic colitis was associated with a wide range of autoimmune diseases, especially of gastrointestinal origin. The results suggest an autoimmune predisposition to microscopic colitis.

Risk of colorectal cancer (CRC) increases in relatives of patients with CRC. The extent to which this is attributable to genetic predisposition or shared environment is unclear. We explored this question using nationwide cohorts from Denmark, Finland and Sweden. From 1977 to 2013, we identified 359 879 individuals with a CRC diagnosis and 2 258 870 of their relatives who we followed for CRC incidence. We calculated standardized incidence ratios (SIR) and 95% confidence intervals (CI) for CRC in individuals with an affected relative. We used nationwide household and pedigree data along with national SIR estimates to calculate risk ratios (RR) for the contribution of shared household environment, childhood environment and genetic relationship to CRC risk in those with an affected relative. SIR of CRC was increased for individuals with an affected relative, across all countries and ages. For those with an affected parent, the SIR was 1.65 (95% CI: 1.61-1.69), 1.98 (95% CI: 1.87-2.09), for those with an affected sibling and 2.14 (95% CI: 1.84-2.49) for those with an affected halfsibling. In those

BACKGROUND: Metformin has pleiotropic effects including anti-inflammatory properties and effects on the gut microbiome. It is primarily used in the older population, where the occurrence of inflammatory bowel disease (IBD) is increasing. The aim of this study was to examine whether metformin protects against development of IBD.METHODS: In the setting of a Danish nationwide population-based cohort, we conducted a nested case-control study using a new-user active comparator design. For each patient with IBD, we selected 10 IBD-free individuals matched on age, sex, and duration of follow-up. Conditional logistic regression was used to estimate odds ratios (ORs) of IBD. Adjustment included educational level, other immune-mediated inflammatory diseases, and use of dipeptidyl peptidase (DPP)-4 inhibitors and statins.RESULTS: Among 302,863 IBD-free new users of oral glucose-lowering drugs, we identified 1271 patients who developed IBD and 12,676 matched IBD-free individuals. Mean age at IBD diagnosis was 66 (SD, 11) years. We found no association between ever use of metformin and risk of IBD, Crohn's disease or ulcerative colitis, adjusted OR 0.95 (95% CI 0.78-1.15), 0.87 (95% CI 0.60-1.26), and 1.04 (95% CI 0.83-1.31), respectively. Neither was the cumulative dose of metformin or the treatment duration with metformin associated with risk of IBD.CONCLUSIONS: In this population-based study, we report that despite anti-inflammatory effects and a notable impact on the gut microbiome, metformin use is not associated with reduced risk of older onset IBD.

ObjectiveAlthough clinical guidelines exist, the diagnostic work-up for diagnosing inflammatory bowel disease (IBD) is complex and varies in clinical practice. This study used real-life data to characterise the current diagnostic procedures used to establish IBD diagnoses in a Danish nationwide setting.DesignPerson-level data on patients diagnosed with IBD between 1 January 2014 and 30 June 2018 were linked between Danish health registers. Information on age, sex, registration of other gastrointestinal diseases, and diagnostic procedures (endoscopies, biopsies, and imaging) performed in relation to the first IBD hospital admission was analysed for the total study population and was stratified by IBD type, sex, and age.ResultsThe majority of the 12 871 patients with IBD included underwent endoscopy (84%), had a biopsy taken (84%), and/or underwent imaging procedures (44%). In total, 7.5% of the population (6% for Crohn’s disease and 8% for ulcerative colitis) were diagnosed with IBD despite not undergoing any of these diagnostic procedures. Patients with Crohn’s disease underwent more procedures than patients with ulcerative colitis (94% vs 92%, pConclusionFor 7.5% of patients with IBD, this study did not detect any registrations of the recommended diagnostic procedures for establishing an IBD diagnosis. Further research is needed to examine whether these findings are mainly explained by limitations of the register data or also indicate shortcomings of the general approach to IBD.

BACKGROUND & AIMS: Safety is a key consideration when choosing advanced therapies (biologic agents and oral small-molecule inhibitors/modulators) in patients with inflammatory bowel diseases (IBDs). We performed a systematic review and meta-analysis comparing the risk of serious infections with advanced therapies in active comparator studies.METHODS: Through a systematic search until February 28, 2022, we included 20 head-to-head studies comparing risk of serious infections with tumor necrosis factor α (TNFα) antagonists, vedolizumab, ustekinumab, tofacitinib, filgotinib, and ozanimod in patients with IBD. We performed random-effects meta-analysis comparing different advanced therapies.RESULTS: No significant difference was observed in the risk of serious infections between vedolizumab vs TNFα antagonists in all patients with IBD (17 cohorts: odds ratio [OR], 0.84; 95% CI, 0.68-1.04), with moderate heterogeneity (I 2 = 37%); on subgroup analysis, vedolizumab was associated with a lower risk of serious infections in patients with ulcerative colitis (11 cohorts: OR, 0.68; 95% CI, 0.56-0.83; I 2 = 0%), but not in Crohn's disease (CD) (9 cohorts: OR, 1.03; 95% CI, 0.78-1.35; I 2 = 42%). Age, sex, prior biologic exposure, and use of biologic monotherapy did not influence this association. In patients with CD, ustekinumab was associated with a lower risk of serious infections vs TNFα antagonists (3 cohorts: OR, 0.49; 95% CI, 0.25-0.93; I 2 = 16%) and vs vedolizumab (3 cohorts: OR, 0.40; 95% CI, 0.17-0.93; I 2 = 67%). Few studies compared other advanced therapies. CONCLUSIONS: Vedolizumab may offer net benefit over TNFα antagonists in patients with ulcerative colitis, but not in CD. Ustekinumab may offer net benefit over TNFα antagonists and vedolizumab in patients with CD.

Background and Aims The health consequences of coronavirus disease 2019 [COVID-19] among patients with ulcerative colitis [UC] and Crohn’s disease [CD] remain largely unknown. We aimed to investigate the outcomes and long-term effects of COVID-19 in patients with UC or CD. Methods We conducted a prospective, population-based study covering all Danish patients with CD or UC and confirmed COVID-19 between January 28, 2020 and April 1, 2021, through medical records and questionnaires. Results All 319 patients with UC and 197 patients with CD who developed COVID-19 in Denmark were included in this study and compared with the Danish background population with COVID-19 [N = 230 087]. A significantly higher risk of COVID-19-related hospitalization was observed among patients with UC (N = 46 [14.4%], relative risk [RR] = 2.49 [95% confidence interval, CI, 1.91–3.26]) and CD (N = 24 [12.2%], RR = 2.11 [95% CI 1.45–3.07]) as compared with the background population (N = 13 306 [5.8%]). A similar pattern was observed for admission to intensive care (UC: N = 8 [2.51%], RR = 27.88 [95% CI 13.88–56.00]; CD: N = 3 [1.52%], RR = 16.92 [95% CI 5.46–52.46]). After a median of 5.1 months (interquartile range [IQR] 4.5–7.9), 58 [42.3%] and 39 [45.9%] patients with UC and CD, respectively, reported persisting symptoms which were independently associated with discontinuation of immunosuppressive therapies during COVID-19 (odds ratio [OR] = 1.50 [95% CI 1.07–10.22], p = 0.01) and severe COVID-19 (OR = 2.76 [95% CI 1.05–3.90], p = 0.04), but not with age or presence of comorbidities. Conclusion In this population-based study of 516 patients with IBD and COVID-19, 13.6% needed hospitalization and 2.1% required intensive care. Furthermore, sequelae were frequent, affecting 43.7% of COVID-19-infected patients. These findings might have implications for planning the healthcare of patients in the post-COVID-19 era.

Interleukin 6 (IL-6) is a multifunctional cytokine with both pro- and anti-inflammatory properties with a heritability estimate of up to 61%. The circulating levels of IL-6 in blood have been associated with an increased risk of complex disease pathogenesis. We conducted a two-staged, discovery and replication meta genome-wide association study (GWAS) of circulating serum IL-6 levels comprising up to 67 428 (ndiscovery = 52 654 and nreplication = 14 774) individuals of European ancestry. The inverse variance fixed effects based discovery meta-analysis, followed by replication led to the identification of two independent loci, IL1F10/IL1RN rs6734238 on chromosome (Chr) 2q14, (Pcombined = 1.8 × 10−11), HLA-DRB1/DRB5 rs660895 on Chr6p21 (Pcombined = 1.5 × 10−10) in the combined meta-analyses of all samples. We also replicated the IL6R rs4537545 locus on Chr1q21 (Pcombined = 1.2 × 10−122). Our study identifies novel loci for circulating IL-6 levels uncovering new immunological and inflammatory pathways that may influence IL-6 pathobiology.

The prevalence of inflammatory diseases is increasing in populations throughout the industrialized world. An increasing proportion of human populations grow up and live in urban areas, probably with reduced exposure to biodiversity, including diverse soil biotas. Decreased exposure to microorganisms from natural environments, in particular in early childhood, has been hypothesized to hamper development of the human immune system and lead to increasing risks of inflammatory diseases, such as asthma. We investigated 40,249 Danish individuals born 1995-2015. Percentage greenspace was assessed in a 2 km buffer around home addresses of individuals. The Danish Biodiversity Map, charting occurrence density of red-listed animals, plants and macrofungi, was used as a proxy for multi-taxon biodiversity. For asthma defined broadly, we found no evidence of decreasing risk of developing asthma with higher levels of biodiversity, while greenspace exposure was associated with higher risk of asthma. In contrast, exposure to total and biodiverse greenspace was associated with reduced risk of developing severe asthma. Exposure to farmland, which in Denmark is heavily industrialized cropland, also showed association with elevated risk of developing asthma, even at relatively low agricultural landcover. In the subset of children growing up in highly urbanized settings, we found high exposures to urban greenspace to be associated with reduced risk of developing asthma. Our results lend limited support to the hypothesis that childhood exposure to biodiverse environments reduces the risk of acquiring inflammatory diseases later in life. However, access to urban greenspace, such as parks, which typically harbour low levels of biodiversity, seems to reduce asthma risk, potentially through exposure to common soil microbiota. Our results suggest that effects of biodiversity exposure on human health is set by a balance between ecosystem services and disservices and that biodiversity conservation is best motivated with other arguments than reduction of risks from inflammatory diseases.

BACKGROUND: Patients with inflammatory bowel disease (IBD) are at increased risk of human papillomavirus (HPV) related cancers such as anal squamous cell carcinoma. However, risk of non-malignant HPV infection has never been systematically studied in IBD. This study aims to assess the risk of genital warts (GW) in IBD patients.METHODS: Using the Danish nationwide registries, we identified 49,163 patients with IBD between 1996 and 2018 and matched them to 491,665 individuals from the general population by age, sex, and HPV immunisation. Cumulative incidence rates for GW in IBD and non-IBD patients were calculated by age. Cox proportional regression analysis was used to calculate hazard ratios (HR) for GW in IBD compared to matched population and in Crohn's disease (CD) compared to ulcerative colitis (UC). We undertook subgroup analysis for risk of GW by sex, year of IBD diagnosis, contraceptive exposure and IBD treatment exposure.RESULTS: The fully adjusted HR for GW in IBD patients compared to the matched non-IBD population was 1.33 (95% CI: 1.19-1.49) and 1.13 (95% CI: 1.01, 1.27) in CD as compared to UC. This increased risk was particularly observed in female (HR: 1.54, 95% CI: 1.33-1.79) over male (HR: 1.14, 95% CI: 0.97-1.34) IBD patients, but was also found across all periods of diagnosis with IBD, regardless of contraceptive treatment exposure, and also seen in IBD patients who had never been exposed to immunosuppressive treatment (HR: 1.33, 95% CI: 1.19-1.49).CONCLUSION: In this nationwide, population-representative cohort study, we observed a 33% increased risk of GW in patients with IBD compared to the matched population and a 13% increased risk of GW in CD compared with UC. This risk was particularly increased in female over male IBD patients and seen independent of IBD treatment exposure.