Accuracy of fecal lactoferrin and other stool tests for diagnosis of invasive diarrhea at a Colombian pediatric hospital

Objectives. Estimate under "real life" conditions the operating characteristics of several stool tests for determining whether a diarrheal episode is invasive-inflammatory. Design. Determination of operating characteristics of diagnostic tests against a standard in a prospectively gathered sample. Setting. The emergency room of the largest Social Security Pediatric Hospital in Colombia serving referred and nonreferred patients. Patients. Stool samples from children attending the emergency room because of acute diarrhea (three or more loose stools per day lasting <7 days). Patients receiving antibiotics or antiparasitic medications were excluded. Interventions, Samples were collected in sterile containers and examined immediately for protozoa, fecal leukocytes, occult blood and lactoferrin, Specimens were inoculated onto culture media for common bacterial fecal pathogens except enteroinvasive Escherichia coli and Clostridium difficile. Main outcome measure. Sensitivity, specificity and likelihood ratios of several cutoff levels for fecal lactoferrin, fecal leukocytes and occult blood. Results. Stool samples from 500 infants and children with diarrhea were collected. Patients' median age was 2.66 years (range, 0.5 to 13 years), and 261 (52.2%) were males. In 155 (31%) cases enteroinvasive bacteria and/or Entamoeba histolytica were documented. Fecal leukocytes >5 had the best sensitivity (63.2%; 95% confidence interval, 55.4 to 70.5) and specificity (84.3%; 95% confidence interval, 80.2 to 87.9), although not statistically or clinically significantly different from lactoferrin. Conclusions. No single test or combination had satisfactory operating characteristics. Nevertheless the use of likelihood ratios derived here can help clinicians identify invasive-inflammatory diarrheal episodes in many instances.