Do systemic symptoms predict the risk of kidney scarring after urinary tract infection?

Background and aims: In the NICE guideline on childhood urinary tract infection (UTI), it is assumed that the presence or severity of systemic symptoms, especially fever, predicts for renal scarring, and different management is recommended accordingly. We aimed to test this hypothesis by retrospective case note analysis. Design and subjects: Notes of children aged under 5 years referred with a first UTI who were assessed for scarring were reviewed. Main outcome criteria: Ability to predict for single or multiple scarring from age, sex, fever, vomiting or anorexia or malaise, or need for hospitalisation, within the age bands used by NICE. Results: There were 51 (65% girls) scarred and 140 (69% girls) unscarred children. Fever, systemic symptoms and hospitalisation were all commoner among younger children (< 6 months vs 6 months-3 years vs > 3 years; fever 0.67 vs 0.38 vs 0.38; systemic symptoms 0.78 vs 0.62 vs 0.43; hospitalisation 0.67 vs 0.29 vs 0.19; p < 0.001 for all). Having vomiting, anorexia or malaise at presentation correlated weakly with single or multiple renal scarring (R-2 = 0.03; p = 0.02), but sex, age, fever or hospitalisation did not (p > 0.5 for all). Sensitivity and specificity data, and plots of proportionate reduction of uncertainty showed that none of these variables was useful for predicting any scarring in children aged < 3 years and that they were only weakly predictive in older children. Conclusions: Clinical signs at presentation in childhood UTI cannot be used to predict for mild or multiple scarring, and should not be used to guide management. NICE's recommendation to do so is not justified.