Evaluation of the accuracy of leukocyte esterase testing to detect pyuria in young febrile children: prospective study.

OBJECTIVE: To study the accuracy and clinical application of the dipstick leukocyte esterase test in the detection of pyuria in young febrile children suspected to have urinary tract infection. DESIGN: Prospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: Urine samples were taken from 215 children younger than 2 years who were suspected to have urinary tract infection (fever without an obvious focus of infection). MAIN OUTCOME MEASURES: The accuracy of the dipstick leukocyte esterase test in detecting significant pyuria defined as a leukocyte count >or=10 mm(3) (>or=0.01 x 10(9) /L). RESULTS: Two hundred and fifty-four urine samples collected by bag, midstream clean-catch, suprapubic bladder aspiration, or urethral catheterization were examined. Using urine microscopy results as a reference, the sensitivity and specificity of the leukocyte esterase test in detecting significant pyuria were found to be 72.0% and 85.8%, respectively; the positive and negative predictive values were 55.4% and 92.6%, respectively; and the positive and negative likelihood ratios were 5.1 and 0.3, respectively. CONCLUSIONS: The dipstick leukocyte esterase test cannot accurately detect pyuria in young febrile children. It is also not appropriate as a screening test to exclude pyuria, reduce the need for the microscopic examination of urine, or indicate when a hospital admission for probable urinary tract infection is needed.