Many patients with diarrhoea undergo colonoscopy.
If this is macroscopically normal, random biopsies are obtained to rule out microscopic colitis, but most patients have functional disease.
Accurate predictors of microscopic colitis could avoid the need to take biopsies in a substantial proportion of patients, saving money for the health service.
Dr John Kane and colleagues from the United Kingdom validated a previously described diagnostic scoring system for microscopic colitis, and incorporated further variables to assess whether this improved performance.
The team included consecutive adults with loose stools undergoing colonoscopy.
Demographic and symptom data were collected prospectively.
|11% of had microscopic colitis|
|Scandanavian Journal of Gastroenterology|
The diagnostic scoring system described previously was applied.
The researchers assessed the incorporation of further variables, including drugs associated with microscopic colitis, number of stools, nocturnal passage of stools, and duration of loose stools, into the scoring system.
Sensitivities, specificities, and positive and negative predictive values were calculated.
Among 242 patients, 11% of whom had microscopic colitis, a cut off of ≥4 on the original scoring system had a sensitivity of 92% and specificity of 35%.
Nocturnal passage of stools and duration of loose stools <6 months were significant predictors of microscopic colitis.
The researchers found that incorporating these variables in a new scoring system with a cut off of ≥6 identified microscopic colitis with 96% sensitivity and 46% specificity.
Dr Kane's team concluded, "Incorporating nocturnal passage of stools and duration of loose stools into the scoring system may improve ability to predict microscopic colitis, and avoid random colonic biopsies in a greater proportion of patients with loose stools."