The epidemiology of microscopic colitis: a 10-year pathology-based nationwide Danish cohort study

Rifaximin Treatment of Collagenous Colitis: A Randomised, Double-Blind, Placebo-Controlled Trial

Introduction

Collagenous colitis (CC) is a disabling disease primarily affecting elderly women. Sparse, well-documented treatment modalities exist, except for budesonide. Long-term and repetitive treatment with budesonide is often necessary. Rifaximin is a poorly absorbed antibiotic with a positive modulatory effect on gut microbiota. In this randomised, double-blind, placebo-controlled single-centre trial, we test the effect of adding rifaximin in continuation to budesonide on relapse rates in CC.

Methods

Eligible patients with active, biopsy-verified CC received oral budesonide during a 6-week open-label induction phase. Patients in clinical remission after 4 weeks of treatment were randomised to receive either rifaximin or placebo for 4 weeks.

Results

Fifteen patients were randomised to receive either rifaximin (n = 7) or placebo (n = 8). At 12-week follow-up, 2 patients in the rifaximin group were still in remission and none in the placebo group (p = 0.2). The median number of days in remission in the rifaximin group was 42 (interquartile range [IQR] 33-126) compared to 18.5 (IQR 10.5-51.5) in the placebo group (p = 0.189). At 12-week follow-up, the relapse rate per 100 person-days in the placebo group was higher (3.25 [1.40-6.41]) than in the rifaximin group (1.33 [0.43-3.10]).

Conclusion

Although not statistically significant (p = 0.0996), the study suggests a potential improvement in relapse rates within the rifaximin group compared to the placebo group. A major limitation in the study is the small sample size.

The colitis may be microscopic, but the diarrhea is not: update on the treatment of microscopic colitis and immune checkpoint inhibitor colitis

PURPOSE OF REVIEW

Microscopic colitis is an inflammatory disease of the colon that presents as watery diarrhea with minimal to normal endoscopic changes on colonoscopy. It encompasses two common subtypes, lymphocytic colitis and collagenous colitis, which are both treated similarly.Immune checkpoint inhibitor colitis is among the most common immune-related adverse events. Endoscopic and histological findings range from normal colonic mucosa to inflammatory bowel like changes. This review article provides update in treatment and management of microscopic colitis and immune checkpoint inhibitor colitis (ICPi colitis).

RECENT FINDINGS

Recent studies on microscopic colitis have focused on the successful use of immunomodulators such as biologics for treatment of budesonide refractory microscopic colitis cases. Microscopic colitis does not confer an added risk for colorectal cancer.With the increasing usage of immunotherapy agents, immune checkpoint inhibitor colitis is becoming more common. ICPi colitis can be successfully managed with steroids, with treatment stepped up to biologics for moderate to severe cases or for mild cases that do not respond to steroids. Immunotherapy agents can be carefully re-introduced in mild cases, after treatment of ICPi colitis.

SUMMARY

Biologics can be used to treat budesonide refractory microscopic colitis. ICPi colitis can be managed with steroids and biologics in moderate to severe cases.

Microscopic Colitis in a Young Male: Unveiling the Rarity

In recent decades, microscopic colitis (MC) has become increasingly recognized as a common contributor to diarrhea and lower gastrointestinal symptoms, particularly among the older demographic. The condition is distinguished by persistent diarrhea with loose watery stools, and endoscopic examination is typically normal with characteristic histopathologic findings. MC is rarely seen under 30 years of age and is less common in males. Our case highlights an exceedingly uncommon clinical setting as it involves a young male who was diagnosed with collagenous colitis. The diagnosis of MC can easily be missed by physicians during initial evaluation. Specifically in irritable bowel syndrome patients with diarrhea predominant symptoms, a colonoscopy should be performed and biopsies should be taken from the entire colon to rule out MC.

Microscopic Colitis: A Review Article

Microscopic colitis (MC) is a chronic inflammatory disease that affects the older population. Its clinical presentation includes a variety of gastrointestinal manifestations. The main symptom is chronic watery, nonbloody diarrhea. The disease has a female predominance. The diagnosis might be challenging since the symptoms are similar to other differential diagnoses, such as celiac disease, irritable bowel syndrome, Crohn's disease, bacterial overgrowth, and infectious colitis. The golden diagnostic tool for diagnosis is performing colonoscopy to obtain the colonic biopsy, which demonstrates the characteristic histological evidence needed for diagnosis. The treatment starts with an accurate diagnosis and trial of any possible offending medications. Alternatively, there are many medications, such as bismuth or budesonide, which are very effective in treating this disease. The primary objective of this detailed review is to enhance knowledge and understanding of this condition among healthcare providers to guide them with detailed information regarding epidemiology, clinical presentation, diagnosis, and appropriate management. In the assessment of individuals presenting with persistent chronic diarrhea, it is essential for healthcare providers to consider MC as a probable differential diagnosis.

Effectiveness of Non-Budesonide Therapies in Management of Microscopic Colitis: A Systematic Review and Meta-analysis

BACKGROUND

Budesonide is accepted as first-choice therapy for microscopic colitis (MC); however, symptoms often recur and some patients may be dependent, intolerant, or even fail budesonide. We performed a systematic review and meta-analysis to determine the effectiveness of non-budesonide therapies (thiopurines, bismuth subsalicylate [BSS], bile acid sequestrants [BAS], loperamide and biologics) for MC suggested by international guidelines.

METHODS

We searched the CENTRAL, MEDLINE, and EMBASE databases from their inception to 18 April 2023 for the above-mentioned therapeutics in MC. We pooled the response and remission rates by medication using a random-effects model.

RESULTS

Twenty-five studies comprising 1475 patients were included in the meta-analysis. Treatment with BSS showed the highest response rate of 75% (95% confidence interval [CI] 0.65-0.83; I² = 70.12%), with 50% achieving remission of symptoms (95% CI 0.35-0.65; I² = 71.06%). Treatment with tumor necrosis factor (TNF) inhibitors (infliximab and adalimumab) demonstrated a response rate of 73% (95% CI 0.63-0.83; I² = 0.00%), with a remission rate of 44% (95% CI 0.32-0.56; I² = 0.00%). The response rate for those treated with vedolizumab was similar; 73% responded to treatment (95% CI 0.57-0.87; I² = 35.93%), with a remission rate of 56% (95% CI 0.36-0.75; I² = 46.30%). Loperamide was associated with response and remission rates of 62% (95% CI 0.43-0.80; I² = 92.99%) and 14% (95% CI 0.07-0.25), respectively, whereas BAS use was associated with response and remission rates of 60% (95% CI 0.51-0.68; I² = 61.65%) and 29% (95% CI 0.12-0.55), respectively. Finally, the outcomes for thiopurine use were 49% (95% CI 0.27-0.71; I² = 81.45%) and 38% (95% CI 0.23-0.54; I² = 50.05%), respectively DISCUSSION: The present systematic review and meta-analysis provides rates of effectiveness of non-budesonide therapies for MC based on available data in the field. Studies in the meta-analysis showed a large amount of heterogeneity due to the variability in assessing the clinical effects of intervention between the studies caused by differences in the definitions of response or remission rates between the studies included. This may likely result in overestimating the benefit of a treatment. Furthermore, the number of participants and drug dosages varied, and only a few studies applied disease-specific activity indices. Only one randomized controlled trial (RCT) was identified. All other 24 included studies were either case series or (retrospective) cohort studies, which complicated efforts to perform further sensitivity analyses to adjust for potential confounders and risk of bias. In addition, the overall evidence on the effect of these treatment options was judged as low, mostly due to comparability bias and the observational nature of the available studies, which limited statistically robust comparisons of rates of effectiveness of the different non-budesonide agents ranked against each other. However, our observational findings may inform clinicians regarding the most rational selection of non-budesonide therapies to patients with MC.

CLINICAL TRIALS REGISTRATION

PROSPERO protocol #CRD42020218649.

Microscopic colitis: Etiopathology, diagnosis, and rational management

Microscopic colitis is an inflammatory bowel disease divided into two subtypes: collagenous colitis and lymphocytic colitis. With an increasing incidence of microscopic colitis exceeding those of ulcerative and Crohn's disease among elderly people in some countries, microscopic colitis is a debilitating life experience. Therefore, physicians should be familiar with its clinical features and management strategies because the disease deserves the same attention as the classical inflammatory bowel diseases. Here, state-of-the-art knowledge of microscopic colitis is provided from a global perspective with reference to etiopathology and how to establish the diagnosis with the overall aim to create awareness and improve rational management in clinical practice. The immune system and a dysregulated immune response seem to play a key role combined with risk factors (e.g. cigarette smoking) in genetically predisposed individuals. The symptoms are characterized by recurrent or chronic nonbloody, watery diarrhea, urgency, weight loss, and a female preponderance. As biomarkers are absent, the diagnosis relies on colonoscopy with a histological assessment of biopsy specimens from all parts of the colon. Although the disease is not associated with a risk of colorectal cancer, a recent nationwide, population-based cohort study found an increased risk of lymphoma and lung cancer. Budesonide is the first-line therapy for management, whereas immunomodulatory drugs (including biologics) and drugs with antidiarrheal properties may be indicated in those failing, dependent, or intolerant to budesonide. In microscopic colitis induced by checkpoint inhibitors, a drug class used increasingly for a wide range of malignancies, a more aggressive therapeutic approach with biologics introduced early seems reasonable. However, particular attention needs to be drawn to the existence of incomplete forms of microscopic colitis with the risk of being overlooked in routine clinical settings.

Quantifying risk factors for microscopic colitis: A nationwide, retrospective cohort study

BACKGROUND

Microscopic colitis (MC) is associated with several risk factors; however, their relative risk has been variable and not thoroughly evaluated. We aimed to quantify the risk of medical comorbidities and medications associated with MC and treatment offered to these patients.

METHODS

A population-based retrospective analysis in International Business Machines (IBM) Explorys (1999-2018), a pooled, de-identified database of 63 million patients in the USA, was performed. Odds ratios (OR) were calculated between MC and other diseases/medications. MC patients were also stratified by age to assess trends of MC in different age groups.

RESULTS

A total of 1130 patients had MC in the database. Among medications, non-steroidal anti-inflammatory agents (OR, 20.2) and proton pump inhibitors (OR, 12.1) were associated with highest odds of MC. Among medical comorbidities, infectious gastroenteritis (OR, 26.6) and celiac disease (OR, 22.5) had the highest odds of being associated with MC. Tobacco smoking, psoriasis, Sjogren's syndrome, Clostridium difficile infection, and malabsorption syndromes all conferred odds greater than 10.

CONCLUSION

Early identification of MC is critical for minimizing morbidity and mortality. Epidemiologic information can be integrated with current clinical algorithms to more rapidly identify patients at risk.

Microscopic Colitis in Denmark: Regional Variations in Risk Factors and Frequency of Endoscopic Procedures

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.

Clinical Characteristics and Treatment Response in Microscopic Colitis Based on Age at Diagnosis: A Multicenter Retrospective Study

BACKGROUND

Microscopic colitis (MC) primarily affects older adults; thus, data in younger patients are scarce.

AIMS

To compare clinical characteristics and treatment response by age at diagnosis.

METHODS

This retrospective cohort study was performed at Mayo Clinic and Massachusetts General Hospital. Patients were chosen consecutively using established databases. Patients were 'younger' if age at diagnosis was ≤ 50 years and 'older' if age > 50 years. Treatment outcomes were captured for induction (12 ± 4 weeks), based on the total number of daily stools, and defined as remission (complete resolution), response (≥ 50% improvement), non-response (< 50% improvement), and intolerance. Patients were considered 'responders' if they had remission or response and 'non-responders' if they had non-response or intolerance.

RESULTS

We included 295 patients (52 younger, 243 older). There were no differences in sex, race, MC subtype, and diarrhea severity between groups (all P > 0.05). Younger patients were more likely to have celiac disease (17.3% vs. 5.8%, P = 0.01), while older patients had higher BMI (mean 25.0 vs. 23.8 kg/m², P = 0.04) were more likely smokers (53.9% vs. 34.6%, P = 0.01) and use NSAIDs (48.6% vs. 15.4%, P < 0.01) and statins (22.6% vs. 3.8%, P < 0.01). Overall treatment response was highest for budesonide (88.3%) and did not differ when comparing older to younger patients (90.6% vs. 77.8%, P = 0.12) or by MC subtype (LC, 81.5% vs. CC, 92.9%, P = 0.07).

CONCLUSIONS

There are no significant differences in MC treatment response based on age or disease subtype. These findings support treating patients with MC based on symptom severity rather than age.

Epidemiology and Clinical Outcomes of Microscopic Colitis: Preliminary Results From the Loyola University Microscopic Colitis Registry (LUMiCoR)

Microscopic colitis (MC) is a common cause of chronic diarrhea with limited long-term data. We searched the pathology records at our institution from 2008 to 2018 to identify cases of MC. Total sample included patients with either a diagnosis of MC or incomplete MC (MCi).Chart review was performed and data were summarized for descriptive statistics. Logistic regression was used to estimate the unadjusted effects of predictors on MC. A total of 216 patients (88.32% white, 80.56% females, mean age 67.12 +/– 15.79) were studied; 50.00% had CC, 40.28% had LC and 9.72% had MCi. Majority (52.31%) were smokers and 21.84% of females were using some form of hormonal therapy. The odds of LC in reference to CC were significantly higher for those using tricyclic antidepressants (TCAs) (OR: 3.23, 95% C.I: 1.18–8.80, p = 0.02). The odds of smoking, statins, aspirin and beta-blocker use were decreased in MCi in reference to CC (all p < 0.05), 29 (74.35%) patients with unresolved symptoms underwent repeat colonoscopies with biopsies. One case of MCi resolved, 8 (72.73%) out of 11 cases of LC resolved, 2 (18.18%) continued to be LC and 1 (9.09%) transformed to CC, 8 (47.06%) out of 17 cases of CC resolved, 8 (47.06%) continued to be CC and 1 (5.88%) transformed to LC. Majority of patients had CC. TCA use resulted in increased odds of LC in reference to CC. Biopsies from repeat colonoscopies in some patients revealed changes in the pathological diagnoses raising the question of interchangeability of MC (CC to LC and vice versa).

Drug-Induced Colitis

Drug-induced colitis encompasses a wide spectrum of colon disorders that can manifest microscopically or macroscopically. Patients present with new-onset colitis or exacerbations of inflammatory bowel diseases; in some cases, colitis resolves with discontinuation of medication. Mucosal injury can be focal or extensive, involving the entire colonic mucosa, and sometimes involves other parts of the gastrointestinal tract. It has been a challenge to determine the proportion of new-onset colitis caused by medication and there are few data on the overall prevalence. We review the drugs that have been linked with development of drug-induced colitis and strategies for physicians who believe their patients have this disorder-usually discontinuation of the drug believed to cause colitis and treatment with steroids or immune-modulating therapies. Physicians must be aware of medications that can cause colitis.

Course of Disease in Patients with Microscopic Colitis: A European Prospective Incident Cohort Study

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.

Microscopic colitis

Microscopic colitis (MC) is an inflammatory disease of the large intestine associated with urgent watery diarrhoea. MC may occur in people of all ages, although the disease primarily affects older women. Once believed to be rare, MC is now known to be a common cause of chronic watery diarrhoea in high-income countries, affecting 1 in 115 women and 1 in 286 men during their lifetime in Swedish population-based estimates. An inappropriate immune response to disturbances in the gut microenvironment is implicated in the pathogenesis of MC. Evidence also supports an underlying genetic basis for disease. The diagnosis of MC relies on clinical symptoms and microscopic assessment of colonic biopsy samples. MC is categorized histologically into collagenous colitis, lymphocytic colitis and their incomplete forms. The mainstay of treatment includes the use of budesonide, with or without adjunctive therapies, and withdrawal of offending drugs. Emerging studies suggest a role for biologicals and immunosuppressive therapies for the management of budesonide-refractory or budesonide-dependent disease. MC can have a substantial negative effect on patient quality of life. The outlook for MC includes a better understanding of the immune response, genetics and the microbiome in disease pathogenesis along with progress in disease management through robust clinical trials.

Disease Activity Patterns, Mortality, and Colorectal Cancer Risk in Microscopic Colitis: A Danish Nationwide Cohort Study, 2001 to 2016

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 <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.

European guidelines on microscopic colitis: United European Gastroenterology and European Microscopic Colitis Group statements and recommendations

INTRODUCTION

Microscopic colitis is a chronic inflammatory bowel disease characterised by normal or almost normal endoscopic appearance of the colon, chronic watery, nonbloody diarrhoea and distinct histological abnormalities, which identify three histological subtypes, the collagenous colitis, the lymphocytic colitis and the incomplete microscopic colitis. With ongoing uncertainties and new developments in the clinical management of microscopic colitis, there is a need for evidence-based guidelines to improve the medical care of patients suffering from this disorder.

METHODS

Guidelines were developed by members from the European Microscopic Colitis Group and United European Gastroenterology in accordance with the Appraisal of Guidelines for Research and Evaluation II instrument. Following a systematic literature review, the Grading of Recommendations Assessment, Development and Evaluation methodology was used to assess the certainty of the evidence. Statements and recommendations were developed by working groups consisting of gastroenterologists, pathologists and basic scientists, and voted upon using the Delphi method.

RESULTS

These guidelines provide information on epidemiology and risk factors of microscopic colitis, as well as evidence-based statements and recommendations on diagnostic criteria and treatment options, including oral budesonide, bile acid binders, immunomodulators and biologics. Recommendations on the clinical management of microscopic colitis are provided based on evidence, expert opinion and best clinical practice.

CONCLUSION

These guidelines may support clinicians worldwide to improve the clinical management of patients with microscopic colitis.

Serotonin in the Pathogenesis of Lymphocytic Colitis

Lymphocytic colitis (LC) is a chronic inflammatory disease associated with watery diarrhea, abdominal pain, and colonic intraepithelial lymphocytosis. Serotonin (5-hydroxytryptamine, 5-HT) is reported to increase in certain colon diseases; however, little is known regarding its metabolism in LC. In the present work, the level of 5-HT in serum and the number of enteroendocrine cells (EECs) as well as the expression of the 5-HT rate-limiting enzyme tryptophan hydroxylase 1 (TPH1) in colonic biopsies and urine 5-hydroxyindoeoacetic acid (5-HIAA) were determined in 36 LC patients that were treated with budesonide and 32 healthy controls. The 5-HT serum and 5-HIAA urine levels were measured using ELISA, the EEC number was determined immunohistochemically, and the colonic TPH1 mRNA expression was determined using RT-PCR. The levels of 5-HT and 5-HIAA and the number of EECs were higher in LC patients than in the controls, and positive correlations were observed between the 5-HT and 5-HIAA levels, 5-HT and EEC number, TPH1 mRNA and EEC number, as well as the severity of disease symptoms and 5-HIAA. Budesonide decreased the levels of 5-HT, 5-HIAA, and TPH1 expression and the number of EECs to values that did not differ from those for controls. In conclusion, the serotonin metabolism may be important for LC pathogenesis, and the urinary level of 5-HIAA may be considered as a non-invasive marker of this disease activity.

Incidence and Prevalence of Microscopic Colitis Between 2001 and 2016: A Danish Nationwide Cohort Study

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 Crohn's disease and ulcerative colitis. However, incidence has stabilised since 2012, suggesting that a plateau has been reached.

Irritable bowel syndrome-like symptoms in treated microscopic colitis patients compared with controls: a cross-sectional study

Background

The prevalence of irritable bowel syndrome (IBS)-like symptoms is high in untreated patients with microscopic colitis (MC), but there is uncertainty of the prevalence of IBS-like symptoms in treated patients. We assessed the degree of IBS-like symptoms in patients with MC in comparison to control subjects, and investigated the association between IBS-like symptoms and faecal calprotectin (FC) in MC patients.

Methods

Patients with an established MC diagnosis (n = 57) were compared to sex- and age-matched controls (n = 138) for scores in the GSRS-IBS (Gastrointestinal Symptom Rating Scale for Irritable Bowel Syndrome) and HADS (Hospital Anxiety Depression Scale). In MC patients, an FC level was simultaneously analysed.

Results

The median interval from MC diagnoses to the time the subjects participated in the study was 5.5 years (25th–75th percentiles; 4.5–9.5 years). The total GSRS-IBS score, subscores for abdominal pain, bloating, and diarrhoea were significantly higher in MC patients compared to controls (all P < 0.001). There was a significant correlation between FC levels and reported bowel frequency (P = 0.023), but there was no correlation between FC levels and GSRS-IBS scores. Patients with MC had significantly higher scores on anxiety (HADS-A) (P < 0.001) and used more selective serotonin-reuptake-inhibitor drugs (P = 0.016) than the control subjects. However, only the control subjects (not the patients with MC) showed significant correlations between GSRS-IBS scores and HADS scores.

Conclusions

Patients with MC reported more IBS-like symptoms and anxiety than control subjects but neither FC levels nor symptoms of affectivity were significantly correlated with IBS-like symptoms.

High risk of microscopic colitis after Campylobacter concisus infection: population-based cohort study

OBJECTIVE

Microscopic colitis (MC) encompasses the two histopathological distinct entities of collagenous colitis (CC) and lymphocytic colitis (LC). In this Danish population-based cohort study, we examined the risk of MC following stool culture with Campylobacter concisus, C. jejuni, non-typhoidal Salmonella or a culture-negative stool test.

DESIGN

We identified patients with a first-time positive stool culture with C. concisus, C. jejuni, non-typhoidal Salmonella or negative stool test, from 2009 through 2013 in North Denmark Region, Denmark, and matched each with 10 population comparisons. All subjects were followed up until 1 March 2018 using Systematised Nomenclature of Medicine codes from The Danish Pathology Register for incident diagnoses of CC and LC. We computed risk and adjusted HRs with 95% CIs for MC among patients and comparisons.

RESULTS

We identified 962 patients with C. concisus, 1725 with C. jejuni, 446 with Salmonella and 11 825 patients with culture-negative stools. The MC risk and HR versus comparisons were high for patients with C. concisus (risk 6.2%, HR 32.4 (95% CI 18.9 to 55.6)), less for C. jejuni (risk 0.6%, HR 3.7 (95% CI 1.8 to 7.7)), low for Salmonella (risk 0.4%, HR 2.2 (95% CI 0.5 to 10.8)) and for patients with negative stool testing (risk 3.3%, HR 19.6 (95% CI 16.4 to 23.4)). After exclusion of the first year of follow-up, the HRs were 9.3 (95% CI 4.1 to 20.1), 2.2 (95% CI 0.9 to 5.4), 1.3 (95% CI 0.2 to 11.1) and 5.6 (95% CI 4.6 to 7.2), respectively.

CONCLUSION

A high risk of MC was observed following C. concisus in stools. Further studies are needed to elucidate any underlying biological mechanisms.

Campylobacter concisus is prevalent in the gastrointestinal tract of patients with microscopic colitis

OBJECTIVES

Microscopic colitis (MC) is potentially induced by an inflammatory reaction to a luminal gut factor. The emerging pathogen Campylobacter concisus is associated with prolonged diarrhoea and subsequently increased risk of MC. We aimed to examine the prevalence of C. concisus in clinical samples from MC patients, analyse the subtypes collagenous colitis (CC) and lymphocytic colitis (LC), and characterise C. concisus isolates from MC patients by genomic sequencing.

METHODS

Mucosal biopsies were collected by sigmoidoscopy in 55 MC patients (CC n = 34, LC n = 21). Saliva and faecal samples were also collected. A two-step cultivation method and PCR established C. concisus prevalence. Biopsy and faecal isolates were sequenced for genomic analysis.

RESULTS

Cultivation revealed C. concisus in saliva 55/55, faeces 14/55 and biopsies 69/436, which was confirmed by PCR in faeces 28/55 and biopsies 215/430. Interestingly, biopsy prevalence was higher in CC patients than in LC patients both by cultivation (50/270 vs.19/166, p = .058) and by PCR (175/270 vs. 40/160, p < .0001). Long disease duration also affected biopsy prevalence both by cultivation 30/244 (<2 years) vs. 39/192 (>2 years) (p = .025) and by PCR 103/239 (<2 years) vs. 112/191 (>2 years) (p = .002). Genomic analysis on sixty biopsy and twenty faecal isolates revealed division into two clusters/genomospecies and a high presence of various, putative virulence genes (zot, exotoxin 9 and hcp).

CONCLUSIONS

Campylobacter concisus was prevalent in MC patients. Interestingly, the biopsy prevalence differed in biopsies from CC and LC patients and with regard to disease duration. Further studies are needed to elucidate this possible association.

Collagenous Colitis Is Associated With HLA Signature and Shares Genetic Risks With Other Immune-Mediated Diseases

BACKGROUND & AIMS

Collagenous colitis (CC) is an inflammatory bowel disorder with unknown etiopathogenesis involving HLA-related immune-mediated responses and environmental and genetic risk factors. We carried out an array-based genetic association study in a cohort of patients with CC and investigated the common genetic basis between CC and Crohn's disease (CD), ulcerative colitis (UC), and celiac disease.

METHODS

DNA from 804 CC formalin-fixed, paraffin-embedded tissue samples was genotyped with Illumina Immunochip. Matching genotype data on control samples and CD, UC, and celiac disease cases were provided by the respective consortia. A discovery association study followed by meta-analysis with an independent cohort, polygenic risk score calculation, and cross-phenotype analyses were performed. Enrichment of regulatory expression quantitative trait loci among the CC variants was assessed in hemopoietic and intestinal cells.

RESULTS

Three HLA alleles (HLA-B∗08:01, HLA-DRB1∗03:01, and HLA-DQB1∗02:01), related to the ancestral haplotype 8.1, were significantly associated with increased CC risk. We also identified an independent protective effect of HLA-DRB1∗04:01 on CC risk. Polygenic risk score quantifying the risk across multiple susceptibility loci was strongly associated with CC risk. An enrichment of expression quantitative trait loci was detected among the CC-susceptibility variants in various cell types. The cross-phenotype analysis identified a complex pattern of polygenic pleiotropy between CC and other immune-mediated diseases.

CONCLUSIONS

In this largest genetic study of CC to date with histologically confirmed diagnosis, we strongly implicated the HLA locus and proposed potential non-HLA mechanisms in disease pathogenesis. We also detected a shared genetic risk between CC, celiac disease, CD, and UC, which supports clinical observations of comorbidity.

Microscopic colitis: pathophysiology and clinical management

Microscopic colitis is a chronic inflammatory disease of the colon that frequently causes chronic watery diarrhoea that might be accompanied by abdominal pain, nocturnal diarrhoea, urgency, and faecal incontinence. These symptoms lead to poor quality of life and increased health-care costs. Diagnosis relies on histological examination of multiple biopsy samples from the colonic mucosa, which often show no or only few abnormalities on endoscopy. Two major histological subtypes can be distinguished-collagenous colitis and lymphocytic colitis-but incomplete and variant forms with fewer characteristic features have been reported. Here we summarise the latest evidence on epidemiology, pathogenesis, and risk factors, and discuss established and novel therapeutic options for clinical remission. Finally, we propose an updated treatment algorithm. Further prospective studies are needed to clarify the natural history of microscopic colitis, supported by validated criteria for the assessment of disease activity.

A nationwide cohort study of the incidence of microscopic colitis in Sweden

BACKGROUND

Epidemiological studies of microscopic colitis have shown varying but increasing incidence rates.

AIM

To assess the incidence of microscopic colitis in Sweden.

METHODS

Nationwide cohort study performed in 1995-2015 based on biopsy reports. Age-specific and age-standardised incidence rates were calculated.

RESULTS

We identified 13 844 patients with an incident diagnosis of microscopic colitis. Lymphocytic colitis (n = 9238) constituted 67% and collagenous colitis (n = 4606) 33% of microscopic colitis. The mean age at time of diagnosis of microscopic colitis was 60.2 years (58.6 for lymphocytic colitis, 63.3 for collagenous colitis). The lifetime risk of developing microscopic colitis was 0.87% in women (95% confidence interval, CI: 0.85-0.88) and 0.35% in men (95% CI: 0.34-0.36). From 2006, the overall incidence of microscopic colitis was approximately 10.5 cases per 100 000 person-years (95% CI: 9.8-11.3) with higher rates in women (72% of cases, incidence rate ratio = 2.4 (95% CI: 2.3-2.5) and the elderly with increasing rates up to 75-79 years. From 2006-2015, there was a significant increase of 1% per year (P = 0.02) in the overall microscopic colitis incidence rate in women; the estimated annual percent change was similar, although not statistically significant, in men (P = 0.15).

CONCLUSIONS

In Sweden, the incidence of microscopic colitis is still increasing in women, although the rate appears to be stabilising. The incidence is particularly high in women and the elderly up to age 75-79 years. Finally, across a lifetime, 1 in 115 females and 1 in 286 males are expected to be diagnosed with microscopic colitis and thus posing a considerable disease burden.

An altered composition of the microbiome in microscopic colitis is driven towards the composition in healthy controls by treatment with budesonide

Background and aim: Microscopic colitis (MC) is an inflammatory disease of the bowel, hypothetically induced by an immunologic response to a luminal microbial agent. We aimed to characterize the microbiome composition in MC and subtypes collagenous colitis (CC) and lymphocytic colitis (LC) and to identify a possible microbial effect of treatment. Method: Stool samples were collected from MC patients prior to treatment, at 8 weeks (during treatment) and at 16 weeks (after treatment), and from healthy controls, not receiving treatment, at matched time-points. Microbiome composition was analyzed by sequencing of the 16S and 18S genes. Differences between patients and controls were analyzed by Shannon's diversity index (mean, standard deviation (SD)) and principal coordinate analysis (PCoA) complemented with a permanova test of UniFrac distances. Results: Ten LC patients, 10 CC patients and 10 controls were included. By PCoA, the bacterial composition in MC patients differed from controls at baseline (p = .02), but not during and after treatment (p = .09 and p = .33, respectively). At baseline, bacterial diversity was lower in MC patients compared to controls (2.5, SD: 0.5 vs 3.5, SD: 0.3, p < .05). Diversity in MC patients increased during (3.0, SD: 0.6) and after treatment and (2.9, SD: 0.5) compared with baseline (p < .01). Eukaryotes were detected in fewer samples from MC patients compared with controls (11/20 (55%) vs. 9/10 (90%), p = .06) with no effect of treatment. Conclusion: Microbiome composition is altered in MC patients. During and after treatment with budesonide the microbiome composition in MC patients was driven towards the composition in healthy controls.

Microscopic colitis: a narrative review with clinical approach

Microscopic colitis (MC) is diagnosed in presence of microscopic alterations of colonic mucosa, in patients without macroscopic lesions who referred for chronic diarrhea. The two types of MC are lymphocytic colitis (LC) and collagenous colitis (CC), but it is unclear whether these are the different expression of one unique disease or if they are distinct conditions. Today, although MC represents a consistent health problem, being responsible for a large part of gastroenterological consultations for diarrhea, it remains often underestimated. The detailed pathogenesis of MC has not been determined yet. Probably, it is the result of an interaction between individual, environmental and genetic factors. The most relevant risk factor for the development of MC is the use of certain drugs (such as non-steroidal anti-inflammatory drugs [NSAIDs], proton pump inhibitors [PPIs], selective serotonin reuptake inhibitors, beta-blockers, statins). Smoking is another relevant factor reported as associated with the development of MC. Diagnosis needs the execution of a colonoscopy in patients complaining about chronic diarrhea and abdominal pain. The crucial role is played by histology: MC is characterized by the presence of colonic mucosal lymphocytic infiltrate, with intraepithelial lymphocytes ≥20 per 100 enteric surface cells, in CC there is a typical subepithelial collagen layer, whose thickness is ≥10 μm. We carried out a review of the current literature to rule out what is new on epidemiology, diagnosis and therapy of MC.

Collagenous colitis without diarrhoea at diagnosis - a follow up study

OBJECTIVE

Chronic watery diarrhoea is a classical symptom of collagenous colitis (CC). However, in some cases, the typical histologic findings of CC can be found in patients without this symptom. In this study we have performed a follow up on patients with a confirmed histological diagnosis of CC without the typical symptom watery diarrhoea.

PATIENTS AND METHODS

A structured medical record follow-up was performed on the subgroup of patients without watery diarrhoea but diagnosed with the typical CC histologic appearance in a previous study of microscopic colitis.

RESULTS

At follow up after a median time of 8 years (range: 0.33-12 years), five of these fifteen patients developed bowel symptoms but only two developed characteristic CC symptoms with watery diarrhoea.

CONCLUSION

The majority of patients without chronic watery diarrhoea at diagnosis remained free from this symptom during follow up and only in a few cases symptoms attributed to CC developed.

Cancer risk in microscopic colitis: a retrospective cohort study

Background

The long-term natural history of microscopic colitis (MC) (collagenous colitis (CC), lymphocytic colitis (LC)), traditionally considered relapsing but non-progressive diseases, is poorly defined. Whether persistent histologic inflammation in such diseases is associated with an increased risk of colorectal neoplasia (CRN) or extracolonic cancers has not been robustly established.

Methods

This retrospective cohort included diagnosed with MC at a referral center. Rates of CRN and extracolonic cancer were compared to patients undergoing screening colonoscopy (n = 306) and to the United States population using data from the Surveillance, Epidemiology, and End-Results (SEER) program. Standardized incidence ratios (SIR) and 95% confidence intervals were calculated and multivariable regression models used to identify the effect of MC diagnosis and severity on cancer risk.

Results

Our study included 221 patients with microscopic colitis (112 CC, 109 LC) among whom 77% were women. Compared to the colonoscopy control population, MC was associated with similar odds of tubular adenoma (Odds ratio (OR) 1.07, 95% CI 0.69–1.66) or villous adenoma (OR 1.26, 95% CI 0.17–9.42). Compared to patients with a single episode of MC, those with 2 or more episodes had similar risk of colon cancer (OR 0.83, 95% CI 0.20–3.39) or tubular adenoma (OR 1.49 95% CI 0.83–2.67). We also identified no statistical increase in the rates of cancer in the MC population compared to US-SEER data.

Conclusion

Microscopic colitis was not associated with increased risk of CRN and extracolonic cancers when compared to controls undergoing colonoscopy or the US SEER population.

Efficacy and Safety of Budesonide, vs Mesalazine or Placebo, as Induction Therapy for Lymphocytic Colitis

BACKGROUND & AIMS

Lymphocytic colitis is a common cause of chronic, nonbloody diarrhea. However, the effects of treatment are unclear and randomized placebo-controlled trials were requested in a Cochrane review. We performed a randomized, placebo-controlled, multicenter study to evaluate budesonide and mesalazine as induction therapy for lymphocytic colitis.

METHODS

Patients with active lymphocytic colitis were randomly assigned to groups given budesonide 9 mg once daily (Budenofalk granules), mesalazine 3 g once daily (Salofalk granules), or placebo for 8 weeks in a double-blind, double-dummy design. The primary endpoint was clinical remission, defined as ≤21 stools (including ≤6 watery stools), in the 7 days before week 8.

RESULTS

The final analysis included 57 patients (19 per group). Most patients were female (72%) and the mean age was 59 years. The proportion of patients in clinical remission at week 8 was significantly higher in the budesonide group than in the placebo group (intention-to-treat analysis, 79% vs 42%; P = .01). The difference in proportions of patients in clinical remission at week 8 between the mesalazine (63%) and placebo groups was not significant (P = .09). The proportion of patients with histologic remission at week 8 was significantly higher in the budesonide group (68%) vs the mesalazine (26%; P = .02) or placebo (21%; P = .008) groups. The incidence of adverse events was 47.4% in the budesonide group, 68.4% in the mesalazine group, and 42.1% in the placebo group.

CONCLUSIONS

In a randomized multicenter study, we found oral budesonide 9 mg once daily to be effective and safe for induction of clinical and histologic remission in patients with lymphocytic colitis, compared with placebo. Oral mesalazine 3 g once daily was not significantly better than placebo. ClinicalTrials.gov no: NCT01209208.

Microscopic colitis in Denmark and Sweden: incidence, putative risk factors, histological assessment and endoscopic activity

OBJECTIVE

The significantly higher incidence rates of microscopic colitis (MC) in Denmark compared to Sweden remains unexplained.

METHODS

Consecutive patients with newly diagnosed MC in the neighbouring regions of Skåne in 2011-2015 and Zealand in 2010-2016 were prospectively identified. Data on large bowel endoscopies and biopsies rates were retrieved. Information on putative factors were obtained from registers and literature. Interobserver agreement between pathologists from both regions on 40 blinded hematoxylin and eosin (H&E)-stained colon biopsies (collagenous colitis (CC), lymphocytic colitis (LC), non-specific inflammation and normal) was evaluated using kappa statistics.

RESULTS

The mean annual incidence per 10⁵ inhabitants in Skåne and Zealand 2010-2015 was 5.9 (95% CI 4.6-7.3) versus 16.4 (95% confidence intervals (95% CI) 13.6-19.2) for CC and 2.7 (95% CI 1.0-4.3) versus 11.1 (95% CI 8.8-13.4) for LC, respectively. Number of endoscopies with biopsy per 1000 and the rate of MC per endoscopy with biopsy was higher in Zealand (34-52/1000) than in Skåne (12-21/1000). The kappa value for overall agreement between pathologists was good (0.72; 95% CI 0.64-0.79). Prescription of proton pump inhibitors and selective serotonin reuptake inhibitors was higher in Skåne in the relevant age groups and prescription of non-steroidal anti-inflammatory drugs and smoking rate higher in Zealand. Alcohol consumption was higher in Denmark than in Sweden.

CONCLUSION

The incidence of MC and number of cases per colonic biopsy was higher in Zealand and could not be readily explained by endoscopy or biopsy rates, differences in histological assessment or putative risk factors.

Prevalence, Pathogenesis, Diagnosis, and Management of Microscopic Colitis

Microscopic colitis (MC), which is comprised of lymphocytic colitis and collagenous colitis, is a clinicopathological diagnosis that is commonly encountered in clinical practice during the evaluation and management of chronic diarrhea. With an incidence approaching the incidence of inflammatory bowel disease, physician awareness is necessary, as diagnostic delays result in a poor quality of life and increased health care costs. The physician faces multiple challenges in the diagnosis and management of MC, as these patients frequently relapse after successful treatment. This review article outlines the risk factors associated with MC, the clinical presentation, diagnosis and histologic findings, as well as a proposed treatment algorithm. Prospective studies are required to better understand the natural history and to develop validated histologic endpoints that may be used as end points in future clinical trials and serve to guide patient management.

Significant association between the use of different proton pump inhibitors and microscopic colitis: a nationwide Danish case-control study

BACKGROUND

Microscopic colitis causes chronic watery diarrhoea and has previously been associated with the use of proton pump inhibitors.

AIM

To explore the association between proton pump inhibitor use and microscopic colitis, including its dependency on timing, dose and choice of proton pump inhibitor.

METHODS

Within a 10-year period, we identified 10 652 patients with a first-time diagnosis of microscopic colitis, including 6254 (59%) with collagenous colitis and 4398 (41%) with lymphocytic colitis. All microscopic colitis cases were histologically confirmed in the Danish Pathology Register. Information on proton pump inhibitor use was obtained from the Danish Prescription Register. In this case-control study, we estimated the adjusted odds ratios (aOR) for the association between proton pump inhibitor use and risk of microscopic colitis using conditional logistic regression while adjusting for potential confounders.

RESULTS

We found strong associations between current proton pump inhibitor use and both collagenous colitis (aOR 6.98; 95% CI: 6.45-7.55) and lymphocytic colitis (aOR 3.95; 95% CI: 3.60-4.33). This association was observed with all PPIs. The strongest association was with the current use of lansoprazole for both collagenous colitis (aOR 15.74; 95% CI: 14.12-17.55) and lymphocytic colitis (aOR 6.87; 95% CI: 6.00-7.86). When considering timing, ORs were highest for current use of proton pump inhibitor and lower for recent or past exposure. No clear dose-response pattern was observed.

CONCLUSIONS

We found a strong association between microscopic colitis and ongoing use of proton pump inhibitors, especially lansoprazole.

Microscopic colitis in patients with ulcerative colitis or Crohn's disease: a retrospective observational study and review of the literature

OBJECTIVES

Onset of microscopic colitis (MC) in patients with ulcerative colitis (UC) or Crohn's disease (CD), or vice versa, has been reported occasionally but the subject is not well described. We therefore report a retrospective observational study of such patients and review the literature.

METHODS

Forty-six Swedish gastroenterology clinics were contacted about patients with diagnoses of both inflammatory bowel disease (IBD) and MC. Publications were searched on PubMed.

RESULTS

We identified 31 patients with onset of MC after a median (range) of 20 (2-52) years after diagnosis of IBD, or vice versa; 21 UC patients developed collagenous colitis (CC) (n = 16) or lymphocytic colitis (LC) (n = 5); nine CD patients developed CC (n = 5) or LC (n = 4); one CC patient developed CD. Of the 21 UC patients, 18 had extensive disease, whereas no consistent phenotype occurred in CD. Literature review revealed 27 comprehensive case reports of patients with diagnoses of both IBD and MC. Thirteen MC patients developed IBD, of which four required colectomy. Fourteen IBD patients later developed MC. There were incomplete clinical data in 115 additional reported patients.

CONCLUSIONS

Altogether 173 patients with occurrence of both IBD and MC were found. The most common finding in our patients was onset of CC in a patient with UC. Although these are likely random associations of two different disorders, MC should be considered in the patient with UC or CD if there is onset of chronic watery diarrhoea without endoscopic relapse of IBD.

Development of a Microscopic Colitis Disease Activity Index: a prospective cohort study

OBJECTIVE

Microscopic colitis (MC) is a common cause of chronic diarrhoea, often with additional symptoms. No validated instruments exist to assess disease activity in MC, making it difficult to compare efficacy of treatments between clinical trials. We aimed to identify clinical features that independently predicted disease severity and create a Microscopic Colitis Disease Activity Index (MCDAI).

DESIGN

Patients with MC were prospectively administered a survey assessing their GI symptoms and the IBD Questionnaire (IBDQ). A single investigator also scored a physician global assessment (PGA) of disease severity on a 10-point scale. Multiple linear regression identified which symptoms best predicted the PGA. These symptoms were then combined in a weighted formula to create the MCDAI. The relationship between MCDAI and the IBDQ was investigated.

RESULTS

Of the 175 patients enrolled, 13 (7.4%) did not complete the survey. The remaining 162 had a median age of 66 years (range, 57-73) and 74% were female. Several clinical features were independently associated with PGA (number of unformed stools daily, presence of nocturnal stools, abdominal pain, weight loss, faecal urgency and faecal incontinence). These parameters were combined to create the MCDAI, which strongly predicted the PGA (R²=0.80). A 1-unit decrease in disease activity (ΔMCDAI) was associated with a 9-unit increase in quality of life (ΔIBDQ).

CONCLUSIONS

The MCDAI strongly predicted the PGA and correlated with a validated measure of quality of life. Several symptoms in addition to diarrhoea are associated with disease severity in MC.

The subtypes of microscopic colitis from a pathologist's perspective: past, present and future

Microscopic colitis (MC) is a chronic inflammatory bowel disease, encompassing a triad of chronic diarrhea, normal endoscopy and characteristic histological findings. MC embraces two histological subtypes described as lymphocytic colitis (LC) and collagenous colitis (CC). The diagnostic criteria of MC were established several years ago and the histological description of LC and CC was based almost exclusively on heamatoxylin-eosin (HE) stained sections. Since the establishment of the diagnostic criteria, important changes have occurred in the concept and diagnostic methods of MC: the emergence of the entity "microscopic colitis incomplete" (MCi), comprising collagenous colitis incomplete (CCi) and lymphocytic colitis incomplete (LCi) and pathologists' increasing use of special stains in everyday diagnostics. The diagnostic challenges of today are threefold: which stains to apply to properly distinguish between MC, MCi and slight inflammatory changes, how to handle cases of diagnostic uncertainty and how to minimize inter observer variability. The views of this article are from the pathologist's perspective. We describe the changes in criteria and diagnostic methods of MC occurring over time, discus pathologists' diagnostic challenges and suggest how these can be met: by automated image analysis of tissue sections and by international collaboration under auspices of the PRO-MC collaboration, a European collaboration on the disease course of MC.

Research progress and perspectives of microscopic colitis

Microscopic colitis (MC) is a common cause of chronic diarrhea. Over the past 20 years, the prevalence of MC has been increasing rapidly, which has aroused the close attention of digestive physicians. The etiology of MC is still unknown, and immune abnormalities are the main pathogenesis, followed by some drugs. MC is clinically characterized by chronic non-bloody watery diarrhea, spastic abdominal pain, weight loss, and fatigue, but colonoscopy is often normal or roughly normal. Colonic biopsy often shows mucosal inflammation or subepithelial collagen band thickening, based on which a diagnosis can be made. At present, there has been no special treatment for MC, with steroid budesonide and immunosuppressive agents being the main treatments. As a self-limiting disease, MC has a good prognosis. Studies have found that MC has a protective effect against colorectal cancer. However, it was recently found that innate immune abnormalities may have carcinogenic effects.

Current Approach to the Evaluation and Management of Microscopic Colitis

PURPOSE OF REVIEW

Microscopic colitis is a common cause of chronic watery diarrhea, particularly in the elderly. The accompanying symptoms, which include abdominal pain and fatigue, can markedly impair patients' quality of life. Diagnosis is based upon characteristic histologic findings of the colonic mucosa. This review focuses on the current approach to evaluation and management of patients with microscopic colitis.

RECENT FINDINGS

Although the incidence of microscopic colitis has been increasing over time, recent epidemiological studies show stabilization at 21.0-24.7 cases per 100,000 person-years. Recent research has further expanded our knowledge of the underlying pathophysiology and emphasized the entity of drug-induced microscopic colitis and the association with celiac disease. Two recent randomized studies have confirmed the effectiveness of oral budesonide for both induction and maintenance treatment of microscopic colitis and is now endorsed by the American Gastroenterological Association as first-line treatment. The incidence of microscopic colitis has stabilized at just over 20 cases per 100,000 person-years. Celiac disease and drug-induced microscopic colitis should be considered in all patients diagnosed with microscopic colitis. There are a number of treatments available for patients with microscopic colitis; however, budesonide is the only option well studied in controlled trials and is effective for both induction and maintenance treatment.

Microscopic colitis: a missed diagnosis among patients with moderate to severe irritable bowel syndrome

OBJECTIVE

Irritable bowel syndrome (IBS) is a very common condition in general practise, affecting 10-20% of the population in the Western world. The clinical picture of diarrhoea-predominant IBS (IBS-D) resembles other chronic diarrhoeic conditions, such as microscopic colitis (MC). It is impossible to separate these by clinical examinations or lab-tests that can be done in general practise. The aim of this study was to detect any missed diagnoses when only using a symptom-based approach for the diagnosis of IBS.

MATERIAL AND METHODOLOGY

We examined 87 participants diagnosed with IBS by the Rome III criteria. All the participants underwent full clinical examination, lab-tests and colonoscopy including mucosa biopsies for histological examination.

RESULTS

The histological analysis revealed four cases of MC in participants who for years had been diagnosed with IBS. We found no biochemical or clinical markers that made it possible to differentiate between IBS and MC. MC was only found in the participants diagnosed with IBS-D.

CONCLUSION

When long-lasting, unresolved diarrhoeic conditions are present in patients over 45-50 years of age, colonoscopy with biopsy should be performed to rule out MC and other pathologies before diagnosing IBS. In younger patients with pronounced watery diarrhoea, one should consider colonoscopy individually if there is no response to IBS-treatment.

Diagnosis and Management of Microscopic Colitis

Microscopic colitis (MC) is a relatively common cause of chronic watery diarrhea, especially in older persons. Associated symptoms, including abdominal pain and arthralgias, are common. The diagnosis is based upon characteristic histological findings in the presence of diarrhea. The two types of MC, collagenous and lymphocytic colitis, share similar clinical features, with the main difference being the presence or absence of a thickened subepithelial collagen band. There are several treatment options for patients with MC, although only budesonide has been well studied in multiple controlled clinical trials. This review will describe the clinical features, epidemiology, pathophysiology, diagnostic criteria, and treatment of patients with MC.

Biomarkers and Microscopic Colitis: An Unmet Need in Clinical Practice

One of the most common causes of chronic diarrhea is ascribed to microscopic colitis (MC). MC is classified in subtypes: collagenous colitis (CC) and lymphocytic colitis (LC). Patients with MC report watery, non-bloody diarrhea of chronic course, abdominal pain, weight loss, and fatigue that may impair patient's health-related quality of life. A greater awareness, and concomitantly an increasing number of diagnoses over the last years, has demonstrated that the incidence and prevalence of MC are on the rise. To date, colonoscopy with histological analysis on multiple biopsies collected along the colon represents the unique accepted procedure used to assess the diagnosis of active MC and to evaluate the response to medical therapy. Therefore, the emerging need for less-invasive procedures that are also rapid, convenient, standardized, and reproducible, has encouraged scientists to turn their attention to the identification of inflammatory markers and other molecules in blood or feces and within the colonic tissue that can confirm a MC diagnosis. This review gives an update on the biomarkers that are potentially available for the identification of inflammatory activity, related to CC and LC.

Microscopic colitis: a descriptive clinical cohort study of 795 patients with collagenous and lymphocytic colitis

OBJECTIVE

Microscopic colitis is a common cause of chronic diarrhoea in the Scandinavian countries. This report comprises demographic data, clinical and endoscopic features, and occurrence of coeliac and inflammatory bowel disease (IBD) in a large urban cohort of patients with lymphocytic colitis (LC) and collagenous colitis (CC).

MATERIALS AND METHODS

A total of 795 patients with microscopic colitis from two hospitals in Stockholm were included. Medical records were reviewed and clinical data, including endoscopic and histological findings, were compiled.

RESULTS

Forty-three percent had CC (female:male ratio 3.7:1) and 57% had LC (female:male ratio 2.7:1). The mean age at diagnosis of CC was 63 years and of LC was 59 years (p = 0.005). Clinical features were similar in both entities, but the intensity of symptoms differed. Watery diarrhoea was reported in 55% in CC patients versus in 43% in LC patients (p = 0.0014), and nocturnal diarrhoea in 28% versus 18% (p = 0.002). Subtle endoscopic mucosal findings were reported in 37% of the CC patients and in 25% of the LC patients (p = 0.0011). Colorectal adenomatous polyps were found in 5.3% of all patients. Coeliac disease occurred in 6% and IBD occurred in 2.1% of all patients.

CONCLUSIONS

Clinical features of LC and CC are similar but not identical. CC seems to be a more severe type of bowel inflammation and LC tends to occur earlier in life. Both forms might indeed feature endoscopic findings despite the designation 'microscopic'. Our study confirms the strong association with coeliac disease.

Prevalence and Natural History of Microscopic Colitis: A Population-Based Study With Long-term Clinical Follow-up in Terrassa, Spain

BACKGROUND AND AIMS

Few studies have assessed the prevalence of microscopic colitis (MC) and the natural history of this disease is not well known. The aim of this study was to evaluate the prevalence rate of MC, the burden of disease in terms of loss of health and the long-term natural history of MC in a population-based cohort study.

METHODS

Cases were obtained from the pathology department registry Hospital Universitari Mutua Terrassa. Belonging to the catchment area, maintaining residence in that area, and being alive on August 31, 2014 were confirmed for each case. Adjusted prevalence rates were calculated. Current active drugs for MC and diarrhoea persistence in every patient were recorded.

RESULTS

The prevalence rate of MC was 107 per 10(5) inhabitants. The rate of patients with active disease, i.e. those representing the true burden of the disease in terms of loss of health, was 31 per 10(5) inhabitants. After a follow-up of 7.8±0.38 years from diagnosis, 75% of the patients experienced prolonged disease remission, defined as clinical remission without requiring drugs for 1 year or more. The only variable associated with prolonged MC remission was how clinical remission was achieved (spontaneous 93.3%, drug-induced, 60.5%; odds ratio 8.4, 95% confidence interval 2.7-26).

CONCLUSIONS

The rate of patients with MC and active disease, which represents the true disease burden in terms of loss of health, is low. Most patients with MC experience prolonged disease remission, with key differences between spontaneous and drug-induced clinical remission.

The Temporal Evolution of Histological Abnormalities in Microscopic Colitis

BACKGROUND AND AIMS

Microscopic colitis (MC) is a common cause of chronic watery diarrhoea but long-term follow-up data are sparse.

METHODS

We performed a retrospective review of health records and all pathology reports in a regional cohort of patients with MC to describe the change in pre- and post-diagnostic colon biopsies.

RESULTS

MC was diagnosed in 468 patients with collagenous colitis (CC), 361 with lymphocytic colitis (LC) and 226 with incomplete MC (MCi). The 2014 incidence of CC, LC and MCi was 14.5, 14.9 and 5 per 10(5). Biopsies from both right and left colon were obtained in 237 (51%) patients with CC, 200 (55%) with LC and 107 (47%) with MCi. The diagnostic sensitivities of both left- and right-sided biopsies for MC were high and did not differ. Pre-diagnostic biopsies were obtained in 150 patients and lamina propria inflammation was described in 59, 47 and 43% of patients with a diagnosis of CC, LC and MCi respectively within 1 year, while histology was normal in 16, 13 and 21%. Post-diagnostic biopsies were obtained in 283 patients. MC persisted for up to one year in 77% with CC, 64% with LC and 45% with MCi, of whom 6, 9 and 18% respectively changed to a different MC subgroup.

CONCLUSIONS

Colonic biopsies obtained prior to the MC diagnosis often revealed increased lamina propria inflammation. The pathological changes of CC and LC are more persistent than those of MCi. Biopsies from the descending or sigmoid colon are sufficient to elucidate whether a patient with chronic watery diarrhoea has MC.

Optimal management of collagenous colitis: a review

Collagenous colitis (CC) is an increasingly recognized cause of chronic inflammatory bowel disease characterized by watery non-bloody diarrhea. As a lesser studied inflammatory bowel disease, many aspects of the CC's natural history are poorly understood. This review discusses strategies to optimally manage CC. The goal of therapy is to induce clinical remission, <3 stools a day or <1 watery stool a day with subsequent improved quality of life (QOL). Antidiarrheal can be used as monotherapy or with other medications to control diarrhea. Budesonide therapy has revolutionized treatment and is superior to prednisone, however, the treatment is associated with high-relapse rates and the management of refractory disease is challenging. Ongoing trials will address the safety and efficacy of low-dose maintenance therapy. For those with refractory disease, case reports and case series support the role of biologic agents. Diversion of the fecal stream normalizes colonic mucosal changes and ileostomy may be considered where anti-tumor necrosis factor (TNF)-α agents are contraindicated. Underlying celiac disease, bile salt diarrhea, and associated thyroid dysfunction should be ruled out. The author recommends smoking cessation as well as avoidance of nonsteroidal anti-inflammatories as well as other associated medications.

CD3 immunohistochemical staining in diagnosis of lymphocytic colitis

Microscopic colitis (MC) is a common cause of chronic watery diarrhea. Traditionally, MC encompasses the 2 subgroups lymphocytic colitis (LC) and collagenous colitis, but recently, an additional subgroup, MC incomplete, has been introduced. Distinguishing between the subgroups relies exclusively on histopathologic evaluation. In the present study, 4 pathologists evaluated 156 archived biopsies originally diagnosed as LC or LC incomplete (LCi). Each pathologist assigned a diagnosis of LC, LCi, or nonspecific inflammation to all cases at 2 independent assessments. At the first assessment, hematoxylin and eosin (HE) stainings were available. At the second assessment, a supplementary CD3 immunohistochemical staining was also available. The aim was to evaluate whether a supplementary CD3 would increase the diagnostic agreement among pathologists, and whether a CD3 stain would change the diagnosis based on HE staining only. After the complete assessment, the cases were divided into 3 groups, that is, full agreement, partial agreement, and disagreement. The CD3 staining increased the number of cases with full agreement from 60 to 78. One hundred thirty-one cases with agreement or partial diagnostic agreement based on HE + CD3 were compared with the HE diagnoses. In 44 (34%) of 131 cases, CD3 changed the diagnosis. Cases assigned to the LCi category based on HE were often changed by a supplementary CD3. Conclusively, it is recommended to use a CD3 before giving the histopathologic diagnosis of LCi.