Rapidly Rising Prevalence of Microscopic Colitis

Purpose: To study the changing prevalence of microscopic colitis over the past 16 years. Methods: A retrospective computerized list of all patients with either lymphocytic colitis or collagenous colitis was obtained from our private community GI practice data base in Orlando, Fl from 1/90- 4/30/06. A breakdown was made of new diagnoses by year. Results: 92 cases of microscopic colitis were identified, 31 (35%) with collagenous colitis, 54 (57%) with lymphocytic colitis, and 7 (8%) with both lymphocytic and collagenous colitis. 14 had remission, then recrudescent disease, an average of 4 years apart, with a range of 1–8 years. There was a distinct change in the prevalence of microscopic colitis from 2004 onward. Whereas 1–5 cases were found annually from 1990 – 2003, (a mean of 3.4cases/year), in 2004 there were 15, in 2005 there were 20 patients, and in the first third of 2006 there were 10 patients. Patients were predominently female, comprising 78% of lymphocytic colitis, 90% of collageous colitis and 83% of those that had both lymphocytic and collagenous colitis. Conclusions: 1. There has been a marked increase in prevalence of microscopic colitis beginning in 2004 with a 200% increase, then a 25% rise in 2005 and a projected 50% rise in 2006. The reasons for this observation are as yet unknown. 2. Lymphocytic colitis is > 3 times as prevalent as collagenous colitis. 3. 15% (N = 14) of patients had remission and then recurrence of symptomatic colitis (8 patients with collagenous and 6 with lymphocytic colitis), an average of 4 years apart. 4. There is a marked female predominance in all forms of microscopic colitis.