Urinary nerve growth factor is a better biomarker than detrusor wall thickness for the assessment of overactive bladder with incontinence

Abstract

To compare the differences in urinary nerve growth factor (NGF) and detrusor wall thickness (DWT) between patients with overactive bladder (OAB) and controls to evaluate their suitability as biomarkers in OAB. A total of 81 patients including normal controls (n = 28), patients with OAB dry (n = 28) and OAB wet (n = 25) were enrolled in this study. Videourodynamic study was performed in 79 patients after confirmation of symptomatic classification by 3-day voiding diary. Urine NGF and DWT measurements were performed at full bladder and urge to void after natural-filling or catheter-filling during videourodynamic study. Urinary NGF level was measured by the ELISA method and DWT was measured by trans-abdominal ultrasound. These two parameters were compared among different symptomatic and urodynamic subgroups. DWT was not significantly different among subgroups at 250 ml bladder volume. Although patients with OAB wet had a significantly greater DWT at the maximal bladder volume, this difference was not significant from controls after correction of the volume factor. By contrast, urinary NGF levels were significantly increased in patients with OAB wet and those with urodynamic detrusor overactivity. However, elevated NGF levels in OAB wet were found only after natural-filling and not after catheter-filling. Urinary NGF level in natural-filling urine sample is a better biomarker for assessment of OAB wet compared to DWT. Patients with OAB dry or hypersensitive bladder did not have an elevated urinary NGF level. Urine samples from catheter-filling do not have a detectably high NGF levels.