Microscopic colitis: the tip of the iceberg?

OBJECTIVES The aims were to determine whether a wide variation exists between hospitals in the diagnosis of microscopic colitis and to assimilate clinical data. DESIGN Retrospective study of 90 patients with microscopic colitis aged between 16 and 92 years from 11 hospitals in south-east England. METHODS A questionnaire was designed to collect relevant data from all patients in whom a new diagnosis of microscopic colitis had been made at the source hospital between January 1990 and December 1996. The inclusion criteria were presentation with watery diarrhoea, a normal endoscopy and a histological report of microscopic colitis. Histology slides were then requested and reviewed. Clinical data were analysed with reference to the confirmed diagnosis. RESULTS The number of patients diagnosed at each hospital ranged between zero and 30, with a median of six. Sixty-eight patients had histological slides reviewed. The numbers of patients with a final reviewed diagnosis of collagenous colitis, lymphocytic colitis and microscopic colitis, type undesignated, were 37, 18 and seven respectively. In thirty-one patients (34%) there was a recent history of the use of non-steroidal anti-inflammatory drugs. CONCLUSIONS These data confirm that there is wide hospital variation in the diagnosis of microscopic colitis. Furthermore, the small group with the undesignated type may be associated with the use of non-steroidal anti-inflammatory drugs.