New European statements and recommendations for the management of microscopic colitis

Microscopic colitis (MC) is a chronic inflammatory bowel disease, divided into collagenous colitis (CC) and lymphocytic colitis (LC). The most common symptom of MC is chronic watery, non-bloody diarrhoea, but other gastrointestinal symptoms such as abdominal pain and bloating are also frequently observed. ¹ The chronic watery diarrhoea leads to great inconveniences for the patient, with faecal urgency, nocturnal stools and faecal incontinence. As the disease may have vague and non-specific signs on endoscopy, histopathological diagnosis is mandatory, which is unfortunately sometimes overlooked. The clinical handling of the patient may be a challenge, because the symptoms may be refractory to conventional treatment. ² In the current issue of the United European Gastroenterology Journal, the United European Gastroenterology and the European Microscopic Colitis Group presents their statements and recommendations for the disease in the European guidelines on microscopic colitis. ³ These guidelines are developed after an impressive research and assessment of published literature within the field. The systematic review was performed in accordance with the PRISMA guidelines, and the GRADE methodology was applied to assess the quality of the studies. Meta-analyses were conducted when applicable. The publication is presented as answers to the most common questions regarding epidemiology, sex differences, lifestyle habits, aetiology and pathogenesis, clinical manifestations, assessment of disease activity, diagnostic criteria and treatment options. For each question and answer, the level of evidence, the strength of recommendation and the degree of consensus within the working group are given. Through this well-structured presentation, the guidelines are easy to understand and to follow.

The report has settled the diagnostic criteria for CC as a thickened subepithelial collagenous band of 10 µm or greater combined with an increased mixed inflammatory infiltrate in the lamina propria. The diagnostic criteria for LC are an increased number of intraepithelial lymphocytes of 20/100 or more surface epithelial cells combined with an increased mixed inflammatory infiltrate in the lamina propria and a normal collagenous band. A third, recently identified subgroup, incomplete MC, is also described. The value of different examinations for the diagnosis of MC is discussed, and common diseases which are important to exclude before the final diagnosis is made. MC is recommended to be ruled out in patients considered to have functional diarrhoea or irritable bowel syndrome with predominant diarrhoea, and all patients with MC should be screened for coeliac disease.

A strict coherence in diagnosing is important, especially when considering chronic diseases which will follow the patients through the rest of their lives. Before the diagnosis of MC is made, even when the histopathological criteria are fulfilled, it must be ascertained that the disease is a chronic disease, and not only a temporary diarrhoea episode due to an infectious gastroenteritis or drug use. ⁴ Overconsumption of alcohol has been described in patients with MC, ⁵ and may be one explanation for chronic diarrhoea, which may be handled quite differently. Misuse of laxatives is another diagnosis to exclude, which may be difficult to identify in women in these age groups. Several systemic diagnoses may have LC as a part of the general syndrome, and the colitis should in these cases be considered as a part of the general disease and not as a separate entity. ⁶ To give the patient an incorrect diagnosis may lead to less optimal treatment and heterogeneous research cohorts, with data difficult to reproduce.

The pooled overall prevalence of MC is estimated to be 119 (95% confidence interval 73–166) per 100,000 inhabitants; LC is slightly more common than CC. ¹ The disease is more common in women than in men. Smoking and some drugs are associated with the disease, although the causal mechanism cannot be proved. Complications commonly associated with Crohn’s disease or ulcerative colitis; for example, malignancy and liver diseases, are not associated with MC. ⁷ Thus, the pathophysiology in MC should differ from the pathophysiology in classic inflammatory bowel disease.

Budesonide is the recommended drug of choice, both for remission and for maintenance of the disease. There is no evidence of severe adverse effects of this drug in long-term use. Faecal calprotectin and histological monitoring are of no use in the course of MC. Instead, the disease activity and clinical remission should be assessed by the Hjortswang criteria. ⁸ When patients fail to respond to budesonide, thiopurines, anti-tumour necrosis factor drugs or vedolizumab can be used in selected patients. Other drugs, such as mesalazine, bismuth subsalicylate, probiotics, corticosteroids and methotrexate, are not recommended.

In conclusion, these guidelines on MC are a very comprehensive review of important background aspects, but most of all, a practical guide on how to handle MC in the everyday work in the clinical praxis.