Nerve Growth Factor Levels are Associated with Overactive Bladder Symptoms and Long-Term Treatment Outcome after Transurethral Resection of the Prostate in Patients with Benign Prostatic Hyperplasia

Purpose: We investigated changes in urinary nerve growth factor in patients with benign prostatic hyperplasia after transurethral prostate resection. We also assessed the association between nerve growth factor and changes of overactive bladder symptoms and long-term treatment outcomes after surgery. Materials and Methods: This was a prospective study of 178 patients at Peking University People's Hospital with benign prostatic hyperplasia between January 2011 and January 2013. Urinary nerve growth factor levels were determined preoperatively using a commercial enzyme-linked immunosorbent assay kit. We also determined prostate volume, I-PSS (International Prostate Symptom Score), quality of life, OABSS (Overactive Bladder Symptom Score), ultrasound estimated post-void residual urine and urodynamics before surgery. Urinary nerve growth factor levels, I-PSS and OABSS were assessed again 1 year after transurethral prostate resection. Results: Urinary nerve growth factor/creatinine levels differed between patients with moderate and severe lower urinary tract symptoms (mean +/- SD 10.513 +/- 4.255 vs 12.334 +/- 4.048 pg/mu mol, p = 0.002). There was no significant difference between patients with grades III/IV and V/VI bladder outlet obstruction (mean 11.285 +/- 4.069 vs 11.781 +/- 4.437 pg/mu mol, p = 0.354). However, differences were significant for urinary nerve growth factor/creatinine levels in patients without overactive bladder, and mild, moderate and severe overactive bladder (mean 8.132 +/- 3.489, 10.128 +/- 3.817, 13.232 +/- 3.290 and 14.029 +/- 3.820 pg/mu mol, respectively, p <0.001). One year after transurethral prostate resection we noted a decrease vs baseline in mean urinary nerve growth factor/creatinine (8.978 +/- 4.022 pg/mu mol, p < 0.001), and I-PSS and OABSS (10.2 +/- 5.4 and 4.3 +/- 3.7, respectively, each p < 0.001). Compared with the good outcome group, the fair/poor group had higher mean baseline urinary nerve growth factor/creatinine (12.319 +/- 4.017 vs 11.015 +/- 4.298 pg/mu mol, p = 0.045), higher mean 1-year urinary nerve growth factor/creatinine (10.847 +/- 4.267 vs 7.850 +/- 3.419 pg/mu mol, p < 0.001) and a lesser mean postoperative change in urinary nerve growth factor/creatinine (1.472 +/- 4.928 vs 3.165 +/- 4.863 pg/mu mol, p = 0.031). Conclusions: Nerve growth factor was associated with overactive bladder symptoms in patients with benign prostatic hyperplasia as well as with the assessment of successful long-term treatment outcome of bladder outlet obstruction with symptoms of overactive bladder.