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.