Urinary tract infections in children: Testing a novel, noninvasive, point-of-care diagnostic marker

Evaluation of diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin in patients with symptoms of urinary tract infections: a meta-analysis

Introduction

Early and accurate diagnosis of urinary tract infection (UTI) can prevent serious sequelae including chronic kidney disease. Multiple individual studies have identified urine neutrophil gelatinase-associated lipocalin (uNGAL) as a promising biomarker for early diagnosis of UTI. We sought to understand the distribution and diagnostic accuracy of uNGAL values in patients presenting with UTI symptoms.

Methods

Our systematic literature reviews in PubMed, Embase, and Cochrane Reviews up to March 2024, identified 25 studies reporting mean/median, standard deviation/quartiles, and detection limits of uNGAL in symptomatic patients with and without culture-confirmed UTI. Seventeen studies were in children. Meta-analyses were performed using the quantile estimation (QE) method estimating the distributions of uNGAL, which were then compared between the UTI and non-UTI groups for identifying the best cut-off points maximizing the Youden index. Sensitivity analyses were performed on all 25 studies including adult patients.

Results

We found that uNGAL levels were significantly higher in samples with confirmed UTI compared to those without. In pediatric studies, median and 95% confidence interval (CI) of uNGAL values were 22.41 (95% CI of 9.94, 50.54) ng/mL in non-UTI group vs. 118.85 (95% CI of 43.07, 327.97) ng/mL in UTI group. We estimated the cut-off point of 48.43 ng/mL with highest sensitivity (96%) and specificity (97%) in children. Sensitivity analysis including both pediatric and adult studies yielded similar results.

Discussion

The level of uNGAL in symptomatic patients with confirmed UTI is much higher than that reported in patients without UTI. It may be used as a diagnostic tool to identify UTI early among symptomatic patients. The range of uNGAL concentrations and cut-off points reported in subjects with UTI is much lower than that reported in patients with acute intrinsic kidney injury.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023370451).

Accuracy of NGAL as a Biomarker for Urinary Tract Infection in Young Febrile Children: An Individual Patient Data Meta-Analysis

OBJECTIVE

To compare the accuracy of urine neutrophil gelatinase-associated lipocalin (NGAL) and leukocyte esterase (LE) for the diagnosis of urinary tract infection (UTI) in children.

STUDY DESIGN

We performed a systematic review and individual patient data meta-analysis of studies that examined urine NGAL as a marker of UTI in children <18 years of age. We created a standardized definition of UTI and applied it to all included children. We compared sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC) of NGAL with LE.

RESULTS

We included individual patient data from 3 studies for a total of 845 children. Included children had a mean age of 0.9 years (SD, 0.6 years). Using a cutoff of 32.7 ng/mL, NGAL had a sensitivity of 90.3% (95% CI: 83.2%-95.0%) and specificity of 93.7% (95% CI: 91.7%-95.4%) for the diagnosis of UTI. LE, using a cutoff of ≧ trace had a sensitivity of 81.1% (95% CI: 72.5%-87.9%) and specificity of 97.0% (95% CI: 95.4%-98.1%). The AUC for NGAL was 0.95 (95% CI: 0.92-0.98). The AUC for LE was 0.90 (95% CI: 0.86-0.93).

CONCLUSION

In young, febrile children, urinary NGAL is more sensitive for the diagnosis of UTI than LE but is slightly less specific.