Test characteristics of tests used to diagnose urinary tract infections in children

Sensitivity | Specificity | Positive likelihood ratio* | Negative likelihood ratio^{¶} | |

Dipstick | ||||

LE | 84% | 78% | 4 | 0.2 |

Nitrite | 50% | 98% | 25 | 0.5 |

Nitrite or LE | 88% | 93% | 13 | 0.1 |

Nitrite and LE | 72% | 96% | 18 | 0.3 |

Microscopy | ||||

Uncentrifuged | ||||

Pyuria (>10/mm^{3}) (all ages) | 77% | 89% | 7 | 0.4 |

Pyuria (>10/mm^{3}) (<2 years) | 90% | 95% | 18 | 0.1 |

Bacteriuria (Gram-stained) | 93% | 95% | 19 | 0.1 |

Overall (P+B) = enhanced | 85% | 99.9% | 85 | 0.1 |

Overall (P or B) | 95% | 89% | 9 | 0.1 |

Centrifuged | ||||

Pyuria (>5/hpf) | 67% | 79% | 3 | 0.4 |

Bacteriuria | 81% | 83% | 5 | 0.2 |

Overall (P+B) | 66% | 99% | 7 | 0.4 |

LE: leukocyte esterase; P: pyuria; B: bacteriuria; hpf: high-power field.

* Positive likelihood ratio: The positive likelihood ratio is the probability that a child with a UTI will have a positive test divided by the probability that a child without a UTI will have a positive test (eg, true positive rate/false positive rate). The higher the positive likelihood ratio, the better the test.

¶ Negative likelihood ratio: The negative likelihood ratio is the probability that a child with a UTI will have a negative test divided by the probability that a child without a UTI will have a negative test (eg, false negative rate/true negative rate). The lower the negative likelihood ratio, the better the test (a perfect test has a negative likelihood ratio of zero).

* Positive likelihood ratio: The positive likelihood ratio is the probability that a child with a UTI will have a positive test divided by the probability that a child without a UTI will have a positive test (eg, true positive rate/false positive rate). The higher the positive likelihood ratio, the better the test.

¶ Negative likelihood ratio: The negative likelihood ratio is the probability that a child with a UTI will have a negative test divided by the probability that a child without a UTI will have a negative test (eg, false negative rate/true negative rate). The lower the negative likelihood ratio, the better the test (a perfect test has a negative likelihood ratio of zero).

References:

- Gorelick MH, Shaw KN. Screening tests for urinary tract infection in children: A meta-analysis. Pediatrics 1999; 104:e54.
- Huicho L, Campos-Sanchez M, Alamo C. Metaanalysis of urine screening tests for determining the risk of urinary tract infection in children. Pediatr Infect Dis J 2002; 21:1.
- Finnell SM, Carroll AE, Downs SM, the Subcommittee on Urinary Tract Infection. Technical report--Diagnosis and management of an initial UTI in febrile infants and young children. Pediatrics 2011; 128:e749.

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