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Introduction: The association of vesicoureteral reflux (VUR) and renal parenchymal damage is well recognized. Renal parenchymal damage associated with VUR can be congenital or acquired. Congenital damage is often renal dysplasia which occurs as a result of abnormal embryological development and is associated with diffuse renal functional abnormalities on dimercaptosuccinic acid (DMSA) scans. Acquired damage results from pyelonephritis induced renal injury mainly associated with focal renal functional abnormalities. The aim of this study was to determine the prevalence and risk factors for diffuse and focal renal functional abnormalities in a large series of children with primary VUR.
Material and Methods: We retrospectively reviewed the medical records and DMSA scans of 1562 consecutive children with primary intermediate (grade III) and high grade (grade IV and V) VUR seen at our institution between 1998 and 2012. Reflux was diagnosed by voiding cystourethrography and DMSA scan was performed to evaluate focal and diffuse renal functional abnormalities. For uni- and multivariate analysis variables associated with renal functional abnormalities such as history of presentation, age, gender and grade of VUR were analyzed in a logistic regression model.
Results: DMSA scans revealed renal functional abnormalities in 409 (26.2%) children (140 boys and 269 girls). Diffuse renal functional abnormalities were detected in 106 (26%) children and focal renal functional abnormalities in 303 (74%) children. Grade III, IV and V reflux was seen in 114 (28%), 243 (59%), 52 (13%) children with renal functional abnormalities, respectively. There were 108 children less than 1 year of age and 301 children were over 1 year of age. Univariate analysis revealed that male gender (OR:2.75 [95%Cl: 1.68-4.50], p<0.001), high grade reflux (OR:2.27 [95%Cl: 1.34-3.84], p=0.002) and children less than 1 year of age (OR:1.78 [95%Cl: 1.06-2.98], p=0.029) were significant risk factors associated with diffuse renal functional abnormalities. Multivariate analysis showed that male gender (OR: 2.48 [95%Cl: 1.50-4.09], p<0.001) and children with high grade reflux (OR:1.96 [95%Cl: 1.14-3.36], p=0.015) were the most significant independent risk factors associated with diffuse renal functional abnormalities.
Conclusion: Our study shows that there is increased risk of diffuse renal functional abnormalities in boys and in children with high grade VUR supporting the theory that congenital damage is mainly seen in boys with high grade VUR. Furthermore children less than 1 year of age are at increased risk for diffuse renal functional abnormalities. Strategies for early detection and treatment of high grade VUR are crucial to avoid possible progression of renal damage.