Objective. The long-term natural history of collagenous colitis (CC) and lymphocytic colitis (LC) is not well known. The few reports available that address these issues have a limited follow-up. The aims of this study were to evaluate the natural history of microscopic colitis (MC), to describe the treatment medications prescribed and to assess the use of non-steroidal anti-inflammatory drugs (NSAIDs) in MC. Material and methods. This study is based on an earlier epidemiological study conducted in Iceland where 125 patients with MC (71 with CC and 54 with LC) were diagnosed in the period 1995-99. All patients still alive and available were questioned about symptoms, treatment and NSAID use in the 3 months preceding the interview. Results. In a mean follow-up time of 6.4 years from diagnosis, 15% of the patients had diarrhoeal symptoms more than once a week, 30% less than once a week and 55% had no diarrhoea. Abdominal pain was reported in 18% of the patients. There was no statistically significant difference in symptoms of CC and LC patients. Forty-eight patients (50%) were receiving medication for MC, 16% used aminosalicylates and 14% corticosteroids. Patients using medication for MC had significantly more diarrhoeal symptoms compared with those who did not (p=0.002). Patients using NSAIDs regularly or as required, statistically did not have more symptoms related to MC than non-NSAID users. Conclusions. Only a minority of patients with MC had diarrhoea more than once a week in a long-term follow-up and the symptom pattern was similar between CC and LC patients. The use of NSAIDs was not associated with more diarrhoeal symptoms.
We express our gratitude to the Scientific Fund of Landspitali University Hospital for financial support. We also thank all the gastroenterologists in Iceland for sharing information in this study and mathematician Örn Ólafsson for his contribution in the field of statistics.