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 characteris tics of several stool tests for determining whether a diarrheal episode is invasive-inflammatory. Design. Determination of operating characteristics of diagnostic tests agai nst a standard in a prospectively gathered sample. Setting. The emergency room of the largest Social Security Pediatric Hospit al 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). Pat ients receiving antibiotics or antiparasitic medications were excluded. Interventions, Samples were collected in sterile containers and examined im mediately for protozoa, fecal leukocytes, occult blood and lactoferrin, Spe cimens were inoculated onto culture media for common bacterial fecal pathog ens except enteroinvasive Escherichia coli and Clostridium difficile. Main outcome measure. Sensitivity, specificity and likelihood ratios of sev eral cutoff levels for fecal lactoferrin, fecal leukocytes and occult blood . Results. Stool samples from 500 infants and children with diarrhea were col lected. Patients' median age was 2.66 years (range, 0.5 to 13 years), and 2 61 (52.2%) were males. In 155 (31%) cases enteroinvasive bacteria and/or En tamoeba histolytica were documented. Fecal leukocytes >5 had the best sensi tivity (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 cl inically significantly different from lactoferrin. Conclusions. No single test or combination had satisfactory operating chara cteristics. Nevertheless the use of likelihood ratios derived here can help clinicians identify invasive-inflammatory diarrheal episodes in many insta nces.