The Swedish Infant High-grade Reflux Trial – Bladder function

Abstract

It has been suggested that infants with high-grade vesicoureteral reflux (VUR) have lower urinary tract dysfunction (LUTD) that is characterised by large bladder capacity (BC) and increased post-void residual (PVR). However, most of these infants have normal or small BC in early infancy and develop large capacity during the first year of life. This study aimed to see whether LUTD development during the infant years in children with high-grade VUR could be prevented by early reflux resolution. For early VUR intervention, endoscopic treatment (ET) was used in a randomised trial comprising 77 infants (55 boys) aged <8 months with VUR grade 4-5 (n=30/n=47); 39 were randomised to antibiotic prophylaxis and 38 to ET. Voiding cystourethrogram, free voiding observation (FVO) and renal scintigraphy were performed at baseline and after 1 year. Bladder capacity and PVR were obtained from FVO. LUTD was defined as a BC of ≥150% of expected and a PVR of ≥20ml. There were no differences in bladder function variables seen between the treatment groups, despite significant differences in VUR resolution. Analysing bladder function related to VUR outcome (VUR grade ≤2 vs grade >2), independent of treatment, showed that VUR grade ≤2 was associated with a smaller BC at 1 year (P=0.050) (a tendency already seen at baseline) and a lower PVR at baseline (P=0.010). PVR increased from baseline to 1 year (P=0.037) in children with grade ≤2 VUR (Summary Table). The group with persistent bilateral grade 5 VUR at 1 year had more abnormal bladder variables compared with other study subjects, with a tendency of larger BC (P=0.057), higher PVR (P=0.0073) and more LUTD (P=0.029) at baseline and a larger BC at 1 year (P=0.016). In explanatory analyses, using logistic regression, a high PVR at baseline was identified as a predictor of VUR grade >2 (P=0.046), persistent bilateral grade 5 VUR (P=0.022), recurrent urinary tract infection (P=0.034), and only a tendency was seen regarding new renal damage (P=0.053). There was no between-group difference seen in bladder function. In children with VUR resolution at follow-up, independent of treatment, BC decreased, whereas PVR increased. High PVR at baseline was a predictive factor for both non-resolution of high-grade VUR and recurrent urinary tract infection. The results suggest that LUTD cannot be prevented by early VUR resolution, but rather is an important prognostic factor for VUR outcome in both endoscopic and prophylactic treatment.