Insights into the development of a new index, vesical adaptation response to diuresis, for understanding lower urinary tract dysfunction.

Objectives: To clarify how vesical adaptation response, the homeostatic system that constantly changes voided volume to adapt to diuresis, is involved in male lower urinary tract symptoms and bladder storage function.

Methods: We included male patients older than 65 years with lower urinary tract symptoms. Vesical adaptation response to diuresis was defined as a positive correlation between urine output rate and voided volume on 3-day sensory-related frequency volume charts. Patients were divided into two groups according to the presence or absence of vesical adaptation response to diuresis, and characteristics were compared between groups.

Results: Ninety-four male patients were finally analyzed. Vesical adaptation response to diuresis was found in 48 patients (51%) and was lacking in 46 patients (49%). Patients without vesical adaptation response to diuresis were significantly more often diagnosed with overactive bladder (P = 0.04). After adjusting for confounders, absence of vesical adaptation response to diuresis was significantly associated with overactive bladder (adjusted odds ratio 3.76, 95% confidence interval 1.34-10.55; P = 0.01) and benign prostatic enlargement (adjusted odds ratio 1.04, 95% confidence interval 1.01-1.07; P = 0.02).

Conclusions: The absence of vesical adaptation response to diuresis, characterized by decreased voided volume during a diuretic phase, can be interpreted as a form of bladder storage dysfunction. Assessment of vesical adaptation response to diuresis may provide a new index of bladder storage function and contribute to a better understanding of the pathophysiology underlying bladder storage dysfunction in patients with lower urinary tract symptoms.