Ethnic factors in the variability of primary vesico-ureteral reflux with age

To determine any ethnic difference in the rate of spontaneous decrease in the incidence of primary vesico-ureteral reflux (VUR).

Voiding cystourethrograms on 738 patients with urinary tract infection were reviewed, and the incidence of primary vesico-urethral reflux was correlated with age, gender and ethnic origin.

There was a gradual decrease in the incidence of primary VUR in whites between 0-10 years, while the incidence of primary VUR in blacks was very low and remained the same. After 10 years of age, no difference was present.

The possibility of delayed maturation of the antireflux mechanism in whites is considered as a possible explanation, and the possibility of an ethnic basis for this is suggested.