Variability of clinical and pressure-flow study variables after 6 months of watchful waiting in patients with lower urinary tract symptoms and benign prostatic enlargement

Purpose: We quantified the physiological variability of clinical and pressure-flow study variables in patients with symptomatic benign prostatic enlargement. Materials and Methods: Symptom scores were measured, and advanced urodynamic studies with pressure-flow analysis were performed in 178 patients before and 6 months after a period of watchful waiting. Results: Patients without bladder outlet obstruction experienced significant symptomatic improvement. Symptoms in patients with obvious bladder outlet obstruction did not improve significantly. The reproducibility of mean pressure-flow variables was evident. However, there was an important intra- individual variability. Patients with obvious bladder outlet obstruction showed a significant decrease in detrusor pressure at maximal flow of 14 cm. water, a significant decrease in the urethral resistance factor of 7 cm. water and a significant decrease of 1 obstruction class on the linear passive urethral resistance relation nomogram, indicating less severe bladder outlet obstruction. Conclusions: Mean differences among therapy groups must be regarded critically, especially when the differences are slight and possibly within physiological variability.