It is a single-center, prospective, interventional, single-arm study. Aim is to investigate which variables are significantly correlated with prolonged anticholinergic treatment (>6 months) in children with overactive bladder (OAB). Investigated variables will include urinary neurotrophins and inflammatory cytokines, sonographic biomarkers, symptom score scale, demographics, and urodynamic findings. Secondary aim is to analyze sensitivity and specificity of urinary biomarkers in diagnosis and management of OAB compared to urodynamics and treatment outcome.