Fecal screening tests in the approach to acute infectious diarrhea: a scientific overview

To evaluate the value of fecal leukocytes, fecal occult blood, fecal lactoferrin and combination of fecal leukocytes with clinical data in the workup of patients with inflammatory diarrhea.

A systematic literature search in all languages using MEDLINE (1970 to 1994), reference lists of articles primarily retrieved and of review articles and correspondence with experts in the field.

The search identified 2603 references, 81 of which were deemed relevant on the basis of prespecified selection criteria. Of these 25 contained sufficient data for further analysis and thus were finally included.

All data from the selected articles were extracted by one observer whereas the second reviewer checked these data for accuracy. True positive rates and false positive rates were calculated from each 2 x 2 table.

The study summarizes the diagnostic accuracy of the signaled tests as predictors of inflammatory diarrhea as defined by stool culture (the reference test). Plots of true positive rates against false positive rates demonstrated widely scattered points, indicating heterogeneity. A summary receiver operating characteristic curve was fitted to the data with the use of logistic transforms and weighted least squares linear regression. Of the 25 studies analyzed 38 data points were used to construct summary receiver operating characteristic curves for index tests.

Fecal lactoferrin was the most accurate index test. Fecal leukocytes showed the lowest performance as assessed by the area under the curve. Occult blood and combination of fecal leukocytes with clinical data yielded intermediate curves. A limited number of studies (fecal lactoferrin, and fecal leukocytes with clinical data) and methodologic flaws identified in the assessed studies must be solved in future primary studies to improve the usefulness of the metaanalytic approach used here.