Urinary nerve growth factor and a variable solifenacin dosage in patients with an overactive bladder

Introduction and hypothesis

We evaluated changes in urinary nerve growth factor (NGF) and NGF/creatinine (NGF/Cr) levels after increasing the dosage of solifenacin in overactive bladder patients.

Methods

The study groups included 59 overactive bladder (OAB) patients and 20 healthy subjects as controls. We measured NGF at baseline for the patients and controls, and used the Overactive Bladder Awareness Tool (OAB-V8) to evaluate urinary symptoms. All patients received a treatment of solifenacin 5 mg for 6 weeks. The responders to treatment served as group 1 and nonresponders received solifenacin 10 mg for an additional 6 weeks. Responders and nonresponders to the 10-mg treatment were defined as groups 2 and 3 respectively. NGF was measured after each treatment using the ELISA method and normalized by the urinary creatinine levels (NGF/Cr).

Results

There were 21, 22 and 16 patients in groups 1, 2, and 3 respectively. At baseline, the NGF and NGF/Cr levels were higher in groups 1, 2, and 3 compared with the controls. After the solifenacin 5 mg treatment, the NGF and NGF/Cr levels of group 1 individuals decreased to those of the control level. After increasing the dosage of solifenacin to 10 mg in group 2, the NGF and NGF/Cr levels decreased to normal levels. In group 3 (patients who did not responded to any treatment), these levels remained unchanged.

Conclusions

Our results suggest that urinary NGF could be a potential biomarker for monitoring the treatment of symptoms in OAB patients who are treated with solifenacin.