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 a 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 decreases in detrusor pressure at maximal flow of 14cm. 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 difference are slight and possibly within physiological variability.