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Development of a Microscopic Colitis Disease Activity Index: a prospective cohort study
  1. Thomas G Cotter1,
  2. Moritz Binder1,
  3. Edward V Loftus Jr2,
  4. Rami Abboud2,
  5. Meredythe A McNally2,
  6. Thomas C Smyrk3,
  7. William J Tremaine2,
  8. William J Sandborn4,
  9. Darrell S Pardi2
  1. 1Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
  2. 2Divisions of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
  3. 3Department of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota, USA
  4. 4Division of Gastroenterology, University of California San Diego, La Jolla, California, USA
  1. Correspondence to Dr Darrell S Pardi, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; pardi.darrell{at}


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.


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  • Contributors TGC: study design, acquisition of data, interpretation of data and drafting of manuscript. MB: analysis and interpretation of data, drafting of manuscript. MAM and RA: study design, acquisition of data. TCS: acquisition of data, critical revision of manuscript for important intellectual content. EVL, WJS and WJT: study concept and design, critical revision of manuscript for important intellectual content. DSP: study concept and design, analysis and interpretation of data, drafting of manuscript and critical revision of manuscript for important intellectual content. All authors approved final version to be published.

  • Funding This work was funded in part by a clinical research grant from the American College of Gastroenterology. EVL has consulted for AbbVie, Amgen, Bristol-Myers Squibb, Eli Lilly, Janssen, Mesoblast, Seres Therapeutics, Sun Pharma, Takeda and UCB Pharma; has received research support from AbbVie, Amgen, Celgene, Genentech, Gilead, Janssen, Medimmune, Receptos, Robarts Clinical Trials, Seres Therapeutics, Takeda and UCB Pharma.

  • Competing interests None declared.

  • Ethics approval Mayo Clinic Institutional Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.