Comparison of hemocytometer leukocyte counts and standard urinalyses for predicting urinary tract infections in febrile infants

OBJECTIVES. METHODS. RESULTS.There were 37 positive urine cultures of at least 1000 CFU/ml. Of these 37 patients, 9 females and 28 males, 1 had a positive blood culture (Escherichia coli). Thirty (81%) of the positive urine cultures had a bacterial colony count ≧100 000 colony-forming units/ml, whereas the remaining had between 1000 and 50 000 colony-forming units/ml. The area under the ROC curve for standard UA was 0.790 ± 0.053, compared with 0.900 ± 0.039 for hemocytometer WBC counts (P < 0.05). For hemocytometer WBC counts, the presence of ≧10 WBC/μl appeared to be the most useful cutoff point, yielding a high sensitivity (83.8%) and specificity (89.6%). Standard UA, with a cutoff point of 5 WBC/high power field, had a lower sensitivity (64.9%) and similar specificity (88.1%). The hemocytometer WBC counts showed significantly greater sensitivity and positive predictive value (83.8 and 60.8%, respectively) than the standard urinalysis (64.9 and 51.1%, respectively) (P < 0.05). The accuracy, specificity and likelihood ratio of hemocytometer WBC counts were also greater than that of standard UA (88.7, 89.6 and 8.08%vs. 84.3, 88.1 and 5.44%). CONCLUSION.