Because hydronephrosis and reflux are reversible, we believe cortical loss represents true renal deterioration in children with spinal dysraphism. Our goal was to better define risk factors for cortical loss.
After institutional review board approval, we reviewed the medical records of 272 children with spinal dysraphism. The following factors were evaluated: age, sex, renal and bladder imaging, urodynamic parameters, medications, catheterization program, continence, infections, and surgical history. Renal cortical loss was defined by scarring or a differential function greater than 15% using a nuclear scan. Univariate and multivariate logistic regression models were fitted to test the associations of specific variables with cortical loss.
Renal cortical loss was found in 41% of children with high-grade reflux vs 2% of children without reflux. Univariate analysis showed only high-grade reflux and female sex to be independent risk factors. Controlling for age and sex, reflux and initiation of catheterization after 1 year of age are significant risk factors. High bladder pressure and hydronephrosis in the absence of reflux were not associated with cortical loss. Multivariate analysis showed that girls with reflux have a 55-fold increased risk of cortical loss.
By limiting the definition of renal deterioration to cortical loss, we identified relevant risk factors: reflux, female sex, and delayed initiation of clean intermittent catheterization. We have also discounted other suspected risk factors: hydronephrosis and elevated bladder pressure. Rather than continuing our focus on hydronephrosis and urodynamics, we believe more research and management debate should be afforded to females with reflux.