Background: Urine dipstick is routinely used for diagnosing urinary tract infection (UTI). It is generally recommended to obtain urine culture from all febrile infants <3 months, while cultures are obtained more selectively in older children. We assessed the performance of the dipstick in different age groups of children <24 months in southern Israel.
Methods: A case-control, retrospective study, conducted between 2015 and 2016. Sensitivity and specificity of urine dipstick result for diagnosing UTI were assessed in various age groups. Additional analyses were done for false negative (FN) and true positive (TP) groups.
Results: Overall, 434 UTI and 571 negative urine culture episodes were included. Dipstick sensitivity was 63% in children <3 months; 93% for supra-pubic aspiration (SPA), and ~50% for non-SPA sampling method. In contrast, sensitivity was >90% for children 3-23 months.
In univariate analysis, younger age; hospitalization; lower temperature, short fever duration; lower blood levels of leukocytes, neutrophils, stabs and CRP; and absent future UTI within <1 year were associated with FN compared with TP (Table 1). In multivariate analysis, among positive culture episodes, age <3 months (odds ratio, OR=6.60), non-SPA sampling method (OR=8.39) and absent future UTI (OR=3.78) were associated with FN.
Conclusions: Dipstick lower sensitivity for diagnosing UTI in febrile infants <3 months, compared with their older counterparts, was associated with non-SPA sampling method, lower inflammatory markers, lower temperature and low risk for future UTI. These findings suggest that positive culture in negative dipstick episodes may not reflect a true UTI.
