The epidemiology of microscopic colitis has been described in Europe, however, no such data exist from North America.
Dr Darrell Pardi and team from Minnesota studied the incidence, prevalence and temporal trends of microscopic colitis in a geographically defined population.
The investigators assessed all who had colon biopsies for evaluation of diarrhea, between 1985 and 2001.
Biopsies were reviewed for confirmation, and to identify missed cases.
The team compared incidence rates, age and sex adjusted to the 2000 US white population.
The investigators used poisson regression to assess the association of calendar period, age and sex with incidence.
|Incidence increased from 1 to 20 per 100,000 by the end of the study|
The investigators identified 130 incident cases for an overall rate of 9 cases per 100,000 person-years.
There was a significant secular trend, with incidence increasing from 1 per 100,000 early in the study to 20 per 100,000 by the end.
The team observed that incidence rates increased with age.
By subtype, the incidence was 3 per 100,000 for collagenous colitis and 6 per 100,000 for lymphocytic colitis.
The investigators found that collagenous colitis was associated with female sex but lymphocytic colitis was not.
Overall prevalence in 2001 was 103 per 100,000.
The team noted that prevalence per 100,000 for collagenous colitis was 39, and 64 for lymphocytic colitis.
Dr Pardi's team concluded, “The incidence of microscopic colitis has increased significantly over time.”
“By the end of the study, the incidence and prevalence were significantly higher than reported previously.”
“Microscopic colitis is associated with older age, and collagenous colitis is associated with female sex.”