Predictive risk factors for chronic renal failure in primary high-grade vesico-ureteric reflux

OBJECTIVE To evaluate and define the risk factors predictive of chronic renal failure (CRF) in children with severe bilateral primary vesico-ureteric reflux (VUR), observed within the first year of life and with a long follow-up. PATIENTS AND METHODS The study comprised 50 patients presenting with grade 3-5 bilateral VUR diagnosed in the first year of life; 12 were suspected prenatally and confirmed shortly after birth, before any urinary tract infection (UTI). The mean (range) follow-up was 6.3 (1-16) years. The variables considered within the first year of life were: gender, prenatal diagnosis with no UTI, number of febrile UTIs, serum creatinine and urea nitrogen levels, metabolic acidosis, proteinuria, 24-h urine output, hypertension, bilateral renal length on ultrasonography and renal scarring on renal scintigraphy. CRF was defined as a creatinine clearance of < 80 mL/min/1.73 m(2) at the last follow-up. The results were assessed using univariate and multivariate analyses (backward-stepwise multiple regression) of the selected variables. RESULTS CRF was detected at the last follow-up in 27 patients (54%), all boys, while renal function was normal in 23 (46%; seven girls). None of the 12 patients with prenatal diagnosis had UTI, but six had CRF. Febrile UTI was the presenting symptom in 38 (76%) patients and 17 (34%) of them had renal scarring. There was no significant difference between the prenatally detected VUR and febrile UTI group in the outcome as CRF. The univariate and multiple regression analysis showed that the first serum creatinine threshold of > 6 mg/L before 1 year old was the most significant risk factor for CRF (P < 0.001; odds ratio 1.25). CONCLUSIONS Children with primary bilateral high-grade VUR and a serum creatinine of > 6 mg/L in the first year of life have a significant risk of developing CRF in the long-term. Prenatal diagnosis and postnatal febrile UTI do not modify the outcome for renal function.