Evaluation of the value of modified nitrite test in early detection of urinary tract infection in children

Abstract

Objective - The study was conducted in order to evaluate the value of the modified nitrite test in the diagnosis of urinary tract infection (UTI) in children.

Patients and methods - The study included 300 children of both sexes, aged 1 month to 14 years who were examined due to suspicion of UTI at the Department of Paediatrics, University Clinical Center Tuzla in the period from August 1, 2006 to August 1, 2007. In relation to the age, the patients were divided into two age groups: from 1 month to 2.0 years and from 2.1 years to 14 years. These groups will further be referred to as the younger and older groups. A cross-sectional study was used to analyze the biochemical examination of urine using test strips (nitrite and modified nitrite test) and the urine culture results.

Results - The described modification of the nitrite test significantly improved its sensitivity (88%) (p=0.001), NPV (96%) (p<0.0001), LR (-) (0.1) and it is more reliable than the nitrite test to exclude the existence of a UTI. The harmony between nitrite and modified nitrite (k=0.66, 95% CI: 0.56, 0.76, p<0.001) and between the modified nitrite test and the urine culture is good (k=0.79, 95% CI: 0.72, 0.87, p <0.001). Through reliability analysis of the modified nitrite test according to the age groups, we found that in the younger age group, after the modification of the nitrite test, its sensitivity was improved (83%), although not significantly (p=0.153), the NPV (94%) (p<0.0001) and LR (-) (0.2) was also improved. The harmony between the nitrite and modified nitrite test was moderate (k=0.59, 95% CI: 0.43, 0.75; p<0.001), and between the modified nitrite test and urine culture it was good (k=0.79, 95% CI: 0.61, 0.87; p<0.001). In the older age group, after the modification its sensitivity was significantly improved (93%) (p=0.001), NPV (98%) (p<0.0001); LR (-) (0.1). The harmony between the nitrite and the modified nitrite test was good (k=0.72, 95% CI: 0.60, 0.85; p<0.001), and between the modified nitrite test and the urine culture it was very good (k=0.84, 95% CI: 0.75, 0.94; p<0.001).

Conclusion - The value of the modified nitrite test is characterized by the improved reliability of the nitrite test to exclude the existence of a UTI, especially in older children, which is important for clinical practice.