Correlation of non-invasive urodynamics with International Prostate Symptom Score (IPSS) and prostate volume

AIM: To study the correlation between non-invasive urodynamic data, the International Prostate Symptom Score (IPSS) and the prostate volume. MATERIALS AND METHODS: Data of 667 healthy volunteers participating in a longitudinal study of changes in urinary bladder contractility secondary to BPE were analyzed. The prostate volume was assessed by transabdominal ultrasonography. Uroflowmetry followed to verify if a minimum free flow rate of 4.5 ml/sec could be achieved. While (re)filling the bladder by drinking, the subjects completed the Dutch version of the IPSS. Next, the bladder pressure was non-invasively measured using the condom catheter method. The urethral resistance (URR) was calculated from the maximum condom pressure and the maximum free flow rate. RESULTS: The IPSS ranged from 0 to 29, (6.1 +/- 4.8) (mean +/- SD), whereas the prostate volumes ranged from 8 to 140 cm3, (34 +/- 18). Twenty eight percent (185/667) of the subjects had a non-invasively quantified high URR and a significantly higher IPSS (7.3 +/- 5.2) than those with a low URR (IPSS (5.7 +/- 4.6)), Mann-Whitney U-test: P < 0.001. The IPSS and the URR were significantly correlated, Spearman's rho (rho) = 0.20, P < 0.001. A significant difference between the prostate volumes, 36 +/- 21 cm3 in the high URR versus 33 +/- 17 cm3 in the low URR group, was not found, P = 0.18. CONCLUSIONS: A weak though statistically significant correlation was found between the non-invasively quantified URR and the IPSS. This suggests that an elevated resistance is a necessary, but not a sufficient condition for lower urinary tract symptoms (LUTS). No correlation was found between the URR and the prostate volume