Systematic Review With Meta-analysis

Diagnostic Overlap of Microscopic Colitis and Functional Bowel Disorders

D. Guagnozzi; Á. Arias; A. J. Lucendo


Aliment Pharmacol Ther. 2016;43(8):851-862. 

In This Article

Abstract and Introduction


Background Microscopic colitis shares certain common clinical manifestations with functional bowel disorders, especially diarrhoea-dominant irritable bowel syndrome (IBS) and functional diarrhoea. However, the exact relationship between microscopic colitis and functional bowel disorders has not been systematically assessed.

Aim To conduct a systematic review and meta-analysis on the diagnostic overlap between functional bowel disorders and microscopic colitis.

Methods We searched MEDLINE, EMBASE and SCOPUS databases, as well as the abstract books of the major gastroenterology meetings, to investigate the prevalence of microscopic colitis among patients with functional bowel disorders (considering all subtypes of both disorders) and vice versa. Data were pooled with a random-effects model.

Results Of 227 references identified, data were collected from 26 studies and a total of 5,099 adult patients. The pooled prevalence any type of functional bowel disorders in patients who present diagnostic criteria of microscopic colitis was 39.1% (95% CI: 22.8–56.6%; I 2: 97%) and was higher for lymphocytic colitis than for collagenous colitis (40.7% vs. 28.4%, respectively; P = 0.58). The prevalence of microscopic colitis in functional bowel disorders patients was 7% (95% CI: 3.6–11.4%), reaching 9.8% (95% CI: 4.4–17.1%; I 2: 95%) in patients exhibiting diarrhoea-dominant IBS, nonsignificantly higher than microscopic colitis rates among patients with constipation-dominant IBS (1.3%) or mixed-dominant IBS (1.9%).

Conclusions There is a significant overlap of symptoms between microscopic colitis and functional bowel disorders, especially in diarrhoeal subtypes. The high proportion of microscopic colitis among diarrhoea-dominant functional syndromes should serve as a call for more active diagnosis in selected patients.


Microscopic colitis (MC) is a term used to identify a group of chronic inflammatory bowel disorders characterised by chronic or recurrent watery diarrhoea in the absence of abnormal radiological examinations, with normal or near-normal endoscopic appearance and specific microscopic abnormalities in colonic biopsies.[1–3] The disorder comprises two major subtypes: lymphocytic colitis and collagenous colitis. The incidence and prevalence of MC have increased over time, making it a common cause of chronic watery diarrhoea worldwide, now estimated to be present in 10–20% of these patients, who otherwise present with a macroscopically normal colon.[4–7] Research over the past decade has indicated an increasing incidence for lymphocytic colitis and collagenous colitis, with some studies noting an incidence at least as high as that of ulcerative colitis and Crohn's disease.[8]

Patients with functional bowel disorders such as irritable bowel syndrome (IBS) – mainly the diarrhoea subtype (IBS-D) – or functional diarrhoea share similar symptoms and endoscopic results with MC patients, with both disorders having a substantial negative impact on health-related quality of life.[9–11]

Irritable bowel syndrome is the most prevalent functional bowel disorder found in the general population worldwide; it is also the most common reason for referral to gastroenterology departments.[12] Its prevalence ranges from 6.2% to 25%, which makes it approximately 100 times more frequent than MC.[13]

As in the case of MC, no distinctive biological, endoscopic or physiological parameters have been defined for IBS, and, in the absence of a colonoscopy with colonic mucosal biopsies, there is no marker for an accurate differential diagnosis between the two conditions.[14] Currently, diagnosis of IBS is symptom-based, with diagnostic criteria for each IBS-subtype as well as for functional diarrhoea. These criteria have been developed to reduce the need for an exhaustive investigation in patients who present no alarm symptoms. However, few validation studies have been carried out on the current gold-standard, symptom-based criteria for diagnosing IBS, namely the Rome III criteria.[15] Indeed, the largest validation study performed to date found only modest accuracy of these criteria in predicting the presence of true IBS.[16]

As opposed to MC, for which corticosteroid-based therapy with budesonide is currently the most effective treatment,[17] therapeutic interventions in IBS are based on antispasmodic agents, changes in dietary habits, and management of stressor conditions, taking into consideration the complex interaction between the digestive, immune and nervous systems in IBS patients.[18]

Interest in proper identification of underlying organic gastrointestinal disease among patients with suspected IBS has increased over the last decade due to the potential implications for its therapeutic management. In particular, several recent studies have reported a diagnostic overlap between MC and IBS (especially in patients with IBS-D or functional diarrhoea) with conflicting results.[19–22] In fact, increased awareness on the part of clinicians, endoscopists and pathologists alike is needed to reach a definitive diagnosis of MC due to the relationship between MC and IBS has neither been universally documented nor assessed according to the latest updated studies.

The aim of this study was to evaluate the frequency of overlap between the diagnostic criteria of IBS or functional diarrhoea and MC. To achieve this goal, we systematically assessed: (i) the prevalence of patients that fulfil the diagnostic criteria for IBS or functional diarrhoea in histologically confirmed MC patients and (ii) the prevalence of histologically confirmed MC patients among patients who fulfilled the diagnostic criteria for IBS or functional diarrhoea.