Interrelationships of bladder compliance with age, detrusor instability, and obstruction in elderly men with lower urinary tract symptoms

Data on the interrelationships of bladder compliance (BC), detrusor instabi lity (DI), and bladder outflow obstruction (BOO) in elderly men with lower urinary tract symptoms (LUTS) are scarce and were therefore assessed in thi s study. Principle inclusion criteria for this study were men aged greater than or equal to 50 years suffering from LUTS as defined by an Internationa l Prostate Symptoms Score (IPSS) of greater than or equal to 7 and a peak f low rate (Q(max)) of less than or equal to 15 ml/sec. Patients with previou s surgery of the bladder, prostate, or urethra as well as a pathological ne uro-urological status were excluded from this study. The following paramete rs were studied in all patients: IPSS, prostate volume calculated by transr ectal ultrasonography, free uroflow study, post-void residual volume determ ined by transurethral catheterization, and a multichannel pressure flow stu dy (P-QS). A group of 170 men were included in the analysis. The mean BC in the overall group was 32 +/- 2 ml/cm H2O (mean +/- standard error of the m ean [SEM]; range, 4-100 ml/cm H2O). In 36.5% of patients, BC was significan tly reduced (less than or equal to 20 ml/cm H2O), and in a further 37.1%, i t ranged from 20 to 40 ml/cm H2O. BC decreased statistically significantly (p < 0.05) in patients with advanced age, lower Q(max), higher voiding pres sures, and larger prostates. In men with DI (n = 61), mean BC was significa ntly lower (22 +/- 3 ml/cm H2O) compared to those without (37 +/- 3 ml/cm H 2O; p = 0.001; n = 109). Patients with severe BOO as defined by a linear pa ssive urethral resistance relationship of greater than or equal to 3 (n = 1 09), had a significantly lower BC (23 +/- 2 ml/cm H2O) compared to those wi thout or minimal obstruction only (39 +/- 3 ml/cm H2O; p = 0.0002; n = 61). Stepwise logistic regression analysis revealed that DI, a low bladder capa city, and a high maximum detrusor pressure were independent predictors of m arkedly reduced BC (<20 ml/cm H2O). BC is decreased in elderly men with hig h voiding pressures, BOG, and DI. The mechanism leading to the reduction of BC under these circumstances is largely unknown and could result from cyto structural alterations of the detrusor and changes in detrusor innervation. Neurourol. Urodynam. 18:3-15, 1999. (C) 1999 Wiley-Liss, Inc.