Microscopic colitis, which includes collagenous and lymphocytic colitis, mainly affects patients who are middle aged or older. There is a female predominance in collagenous colitis.
In this study, physicians performed an epidemiological study of microscopic colitis in a well defined Swedish population.
The team retrospectively searched for patients who had a colonoscopy for non-bloody diarrhea between 1993 and 1998.
|Mean annual incidence of collagenous colitis = 4.9 cases per 105 inhabitants.|
They reassessed 1108 colonic mucosal biopsies from these patients.
The team diagnosed 51 cases (45 female) of collagenous colitis and 46 cases (31 female) of lymphocytic colitis.
They determined that the median age at diagnosis was 64 years in collagenous colitis and 59 years in lymphocytic colitis.
The physicians calculated that the mean annual incidence of collagenous colitis was 4.9 cases per 105 inhabitants. The mean annual incidence of lymphocytic colitis was 4.4 cases per 105 inhabitants.
They established that the annual incidence of collagenous colitis had increased from 3.7 cases per 105 inhabitants between 1993 and 1995 to 6.1 cases per 105 inhabitants between 1996 and 1998.
The annual incidence of lymphocytic colitis also increased: from 3.1 cases 105 inhabitants to 5.7 cases per 105 inhabitants.
Dr Olesen's team concluded, "The annual incidences of collagenous colitis and lymphocytic colitis are higher than considered previously".
"Microscopic colitis was diagnosed in 10% of all patients with non-bloody diarrhea referred for colonoscopy and in almost 20% of those older than 70 years".