Children with symptomatic urinary tract infection in Göteborg 1970-79 followed for two decades

Abstract

Objective: To study a populationbased cohort of subjects, detected after their first known urinary tract infection (UTI) with special focus on: the natural course of vesicoureteral reflux; the prevalence of renal scarring, age at detection and factors of importance for its development; the long term risk of impaired renal function and hypertension. Methods: Analyses of data, prospectively registered during childhood, and an adulthood follow-up investigation evaluating renal function by 51Cr-EDTA clearance and blood pressure by 24-hour ambulatory technique.Results: A total of 1221 children from the city of Göteborg was included 1970-79; reflux was found in 230 and non-obstructive renal scarring in 74. Spontaneous disappearance of reflux was more frequent than previously described. Persistence was relatively longer in those with dilatation and in girls. Most boys had renal scarring established at first investigation during infancy, associated with dilated reflux. In contrast, most girls had acquired scarring that was significantly associated with recurrent febrile UTIs.At the follow-up investigation, 16-26 years after the first UTI, 57 of 68 patients with non-operated scarring as well as 51 matched subjects without scarring participated. The median glomerular filtration rate was 99 ml/min/1.73m2 in both groups. However, during the last decade a significant reduction of individual clearance of scarred kidneys was found, irrespective of gender.Blood pressure did not differ between the scarring and non-scarring group, not even when patients with more extensive or bilateral scarring were analysed separately. The plasma renin-angiotensin-aldosteron activity was similar in the groups, but concentrations of atrial natriuretic protein were significantly higher in the scarring group.Conclusions: There is a high tendency of spontaneous disappearance of reflux, both with and without dilatation. Renal scarring in boys is usually congenital and associated with reflux while it is acquired and associated with recurrent febrile UTIs in girls. Boys and girls with UTI should therefore be described separately in scientific studies. The risk of renal impairment and hypertension in our young adult patients with renal scarring was lower than previously described, most likely as a consequence of early detection and close supervision during childhood. However, further follow-up of this population is warranted to evaluate the loss of function in scarred kidneys and of the blood pressure and its regulation.