1. Childhood urinary tract infections as a cause of chronic kidney disease

2. Objective  Urinary tract infections (UTIs) in childhood are considered a risk for chronic kidney disease (CKD), but this association is poorly verified.  They wanted to determine the etiologic fraction of UTIs in childhood as a cause of CKD.

3.  Urinary tract infections (UTIs) are among the most common bacterial infections in childhood, and 2% to 5% of children experience ≥1 before puberty.  Childhood UTIs are found to cause kidney scarring and are claimed to lead to impaired kidney function later, especially in the presence of vesicoureteral reflux (VUR).  VUR is the backward flow of urine from the bladder into the kidneys. They think this may cause renal scarring.  Therefore, children are subjected to radiologic imaging after the first UTI and long-term antibiotic prophylaxis if grade III to V VUR is found. The most severe consequence of childhood UTIs has been thought to be chronic kidney disease (CKD).

4. Methods  A systematic literature search on the association between childhood UTIs and CKD was conducted, and data for patients with CKD in the area of 1 tertiary care hospital were reviewed.

5. Methods  Data Sources: Firstly, they sought evidence of a causal relationship between childhood UTIs and CKD by performing a systematic literature review. Secondly, they analyzed the causes of CKD among all living patients who were monitored or treated in the departments of internal medicine and pediatrics of Oulu University Hospital. Thirdly, we analyzed the causes of CKD among patients who died before study entry while undergoing renal replacement therapy (RRT). To identify congenital kidney anomalies, they reviewed systemically the results of the first kidney imaging studies for structural abnormalities. VUR was not considered a structural abnormality.

6. Methods  Literature Review  A systematic literature search was conducted with the PubMed database for the period from January 1966 to August 2009  The focus of the review was on the number of childhood UTIs and kidney imaging findings for patients with CKD without a definitive noninfectious cause.

8. Methods  Local Patients  The hospital records of all 366 patients who were treated or monitored because of CKD at the Oulu University Hospital  Patients with VUR, nephrosclerosis, or diseases or malformations affecting only 1 kidney were included in the review analysis. The remaining 58 patients were asked for interviews; 54 (92%) of them gave informed consent and completed a structured questionnaire about childhood UTIs.  The patient records of the 54 patients who gave informed consent were obtained from the community health centers where they had been treated or monitored before the age of 16 years. The patients and their records were identified on the basis of individual social security numbers, which have been issued to every Finnish citizen since 1964.

10. Methods  Registry Data  Data on patients undergoing RRT were collected from the Finnish Registry for Kidney Diseases, which has been estimated to cover 97% to 99% of all Finnish patients who have received RRT since 1964. From this registry, they collected the diagnoses for patients who died before the beginning of the study.

11. Results  The systematic literature search yielded a total of 781 articles, and they used the titles and abstracts to choose 39 for further evaluation. Finally, they found 10 articles, reporting results for 1576 patients, on the childhood UTIs of patients with CKD or the clinically significant, long-term consequences of childhood UTIs  In local patients it was seen that their kidney structures were abnormal when first examined, and those abnormalities could have been observed through ultrasonography.  According to the Finnish Registry for Kidney Diseases, none of the patients in the Oulu University hospital area who were born after 1960 had CKD related to childhood UTIs and died before the beginning of the study.

12. Conclusions  In the absence of serious congenital anomalies, the etiologic fraction of childhood UTIs as a cause of CKD after the first UTI in childhood seems to be small. Imaging procedures after the first UTI can be focused on finding severe urinary tract abnormalities.