Medication use and microscopic colitis: a multicentre retrospective cohort study

Background: Medication use has been implicated in the development of microscopic colitis (MC). However, studies have demonstrated inconsistent findings and there exist variations in design. Aim: To measure the association between medication use and MC. Methods: Patients who underwent a colonoscopy over a 10-year period at two academic medical centres (Columbia University Medical Centre and Mayo Clinic) were identified. Cases were patients with biopsy-proven MC and controls were patients who underwent colonoscopy for evaluation of diarrhoea with biopsies negative for MC. Cases were matched by age, gender and calendar period with up to two controls. Demographics, medication use, smoking history and coeliac disease status were collected. Conditional logistic regression was used with and without adjustment for smoking. Results: A total of 344 patients with MC were matched to 668 controls. After adjusting for smoking, there was an inverse association between MC and use of proton pump inhibitors (PPIs) (OR 0.64; 95% CI 0.47-0.87), H2 blockers (OR 0.46; 95% CI 0.24-0.88) and oral diabetes medications (OR 0.47; 95% CI 0.27-0.81). There was a positive association with nonsteroidal anti-inflammatory drug (NSAID) use and MC (OR 1.63; 95% CI 1.12-2.38). Conclusions: NSAID use was associated with MC, while use of PPIs, H2 blockers and oral diabetes medications were inversely related to MC. Our use of a control group with diarrhoea, as opposed to healthy controls, may have contributed to these inverse associations. Future studies of drug-induced microscopic colitis should include control groups with diarrhoea, and not only healthy controls.