Accuracy of Automated Flow Cytometry-Based Leukocyte Counts To Rule Out Urinary Tract Infection in Febrile Children: a Prospective Cross-Sectional Study.
Automated flow cytometry of urine remains an incompletely validated method to rule out urinary tract infection (UTI) in children. This cross-sectional analytical study was performed to compare the predictive values of flow cytometry and a dipstick test as initial diagnostic tests for UTI in febrile children and prospectively included 1,106 children (1,247 episodes). Urine culture was used as the gold standard test for diagnosing UTI. The performance of screening tests to diagnose UTI were established using receiver operating characteristic (ROC) analysis. Among these 1,247 febrile episodes, 221 UTIs were diagnosed (17.7% [95% confidence interval {CI}, 15.6 to 19.8%]). The area under the ROC curve for flow cytometry white blood cell (WBC) counts (0.99 [95% CI, 0.98 to 0.99]) was significantly superior to that for red blood cell (0.74 [95% CI, 0.70 to 0.78]) and bacterial counts (0.89 [95% CI, 0.87 to 0.92]) (P < 0.001). Urinary WBC counts also had a significantly higher area under the ROC curve than that of the leukocyte esterase (LE) dipstick (0.92 [95% CI, 0.90 to 0.94]), nitrite dipstick (0.83 [95% CI, 0.80 to 0.87]), or the combination of positive LE and/or nitrite dipstick (0.91 [95% CI, 0.89 to 0.93]) test (P < 0.001). The presence of ≥35 WBC/μl of urine was the best cutoff point, yielding both a high sensitivity (99.5% [95% CI, 99 to 100%]) and an acceptable specificity (80.6% [95% CI, 78 to 83%]). Using this cutoff point would have reduced the number of samples sent to the laboratory for culture by 67%. In conclusion, the determination of urinary WBC counts by flow cytometry provides optimal performance as an initial diagnostic test for UTI in febrile children.
Department of Pediatric Nephrology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium.
Hong Phuoc
HP
Duong
Department of Nephrology, UZ Brussel-Vrije Universiteit Brussel (VUB), Brussels, Belgium.
Karl Martin
KM
Wissing
Department of Pediatric Nephrology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium.
Nathalie
N
Tram
Department of Microbiology, Hôpital Universitaire Brugmann, ULB, Brussels, Belgium.
Georges
G
Mascart
Department of Infectious Diseases, Hôpital Universitaire des Enfants Reine Fabiola, ULB, Brussels, Belgium.
Philippe
P
Lepage
Department of Pediatric Nephrology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium khalid.ismaili@huderf.be.
Khalid
K
Ismaili
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001437:Bacteriuria / Q000175:diagnosis*; D002265:Carboxylic Ester Hydrolases / Q000652:urine; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004906:Erythrocyte Count; D005260:Female; D005334:Fever / Q000175:diagnosis* / Q000382:microbiology; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007223:Infant; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009573:Nitrites / Q000652:urine; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016482:Urinalysis / Q000379:methods; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult
D009573:Nitrites; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases
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