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 instability (DI), and bladder outflow obstruction (BOO) in elderly men with lower urinary tract symptoms (LUTS) are scarce and were therefore assessed in this study. Principle inclusion criteria for this study were men aged > or = 50 years suffering from LUTS as defined by an International Prostate Symptoms Score (IPSS) of > or = 7 and a peak flow rate (Qmax) of < or = 15 ml/sec. Patients with previous surgery of the bladder, prostate, or urethra as well as a pathological neurourological status were excluded from this study. The following parameters were studied in all patients: IPSS, prostate volume calculated by transrectal ultrasonography, free uroflow study, post-void residual volume determined by transurethral catheterization, and a multichannel pressure flow study (pQS). 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 mean [SEM]; range, 4-100 ml/cm H2O). In 36.5% of patients, BC was significantly reduced (< or = 20 ml/cm H2O), and in a further 37.1%, it ranged from 20 to 40 ml/cm H2O. BC decreased statistically significantly (p < 0.05) in patients with advanced age, lower Qmax, higher voiding pressures, and larger prostates. In men with DI (n = 61), mean BC was significantly lower (22 +/- 3 ml/cm H2O) compared to those without (37 +/- 3 ml/cm H2O; p = 0.001; n = 109). Patients with severe BOO as defined by a linear passive urethral resistance relationship of > or = 3 (n = 109), had a significantly lower BC (23 +/- 2 ml/cm H2O) compared to those without or minimal obstruction only (39 +/- 3 ml/cm H2O; p = 0.0002; n = 61). Stepwise logistic regression analysis revealed that DI, a low bladder capacity, and a high maximum detrusor pressure were independent predictors of markedly reduced BC (< 20 ml/cm H2O). BC is decreased in elderly men with high voiding pressures, BOO, and DI. The mechanism leading to the reduction of BC under these circumstances is largely unknown and could result from cytostructural alterations of the detrusor and changes in detrusor innervation.