Longitudinal changes in isovolumetric bladder pressure in response to age-related prostate growth in 1,020 healthy male volunteers.

AIM: To non-invasively study if compensation and decompensation occurs in the urinary bladder of healthy male volunteers in response to benign prostatic enlargement (BPE) using the condom catheter method.

METHODS

Between 2001 and 2010, 1,020 healthy male volunteers were included in a longitudinal study based on three non-invasive urodynamic examinations during a 5-year follow-up. Inclusion criteria were an informed consent, the ability to void in a normal standing position and a minimum free flow rate of 5.4 ml/sec. Study parameters were prostate volume (PV), maximum free urinary flow rate (Q(max)) and bladder contractility, quantified by the maximum isovolumetric bladder pressure, measured in the condom (P(cond.max)). Volunteers also completed the International Prostate Symptom Score Form (IPSS).

RESULTS

Within limitations, the included volunteers had a flat age distribution between 38 and 72 years. This made it possible to combine longitudinal analysis in a 5-year observation interval, with cross sectional analysis in a 35-year age range. Longitudinal analysis showed that with increasing age, PV increased with 1.9% per year, whereas Qmax decreased with 1.1% per year. IPSS increased with 1.1% per year when volunteers were older than 55 years. P(cond.max) increased during the 5-year longitudinal follow-up, but not in the cross sectional analysis.

CONCLUSIONS

The difference between cross sectional and longitudinal results of the P(cond.max) may have been caused by compensation of the urinary bladder resulting in a selection effect. This would imply that compensation is a relatively fast process, taking approximately 5 years.