Independent risk factors for renal damage in a series of primary vesicoureteral reflux: A multivariate analysis

SUMMARY Aim:  The aim of this study was to investigate risk factors associated with different extents of renal parenchyma involvement in a paediatric series of primary vesicoureteral reflux (VUR). Methods:  A total of 549 patients with VUR were analyzed. The variable of interest was renal scar, assessed by technetium-99m dimercaptosuccinic acid scan, and classified into three subtypes: focal scar, multiple cortical scarring and diffuse scars with a contracted renal unit. The multinomial regression model was applied to identify independent variables associated with each subtype of renal damage. Results:  After adjustment, four variables remained independently associated with a contracted renal unit: reflux grades III–V (odds ratio (OR) = 9.7; 95% confidence interval (CI) = 4.1–21.0), age at diagnosis (OR = 3; 95% CI = 1.6–5.1), unilateral reflux (OR = 2.1; 95% CI = 1.2–3.8), and male sex (OR = 2; 95% CI = 1.1–3.8). Two variables were associated with multiple scars: reflux grades III–V (OR = 13.8; 95% CI = 7.4–26.0) and age at diagnosis (OR = 1.9; 95% CI = 1.2–3.0). Two variables were associated with a focal scar: reflux grades III–V (OR = 7.9, 95% CI CI = 3.8–16.4) and male sex as a protective factor (OR = 0.5; 95% CI = 0.25–1.0). Conclusion:  Our findings suggest that the development of a contracted renal unit is probably due to congenital malformation, more commonly observed in male infants with high-grade reflux.