Background: Tiotropium is widely used for the treatment of chronic obstructive pulmonary disease (COPD), but it is not usually prescribed for patients with micturition disorder, such as benign prostatic hyperplasia (BPH), because of the potential to increase the risk of acute urinary retention through its anticholinergic effects. However, no data are available to prove a true causal relationship between tiotropium and lower urinary tract dysfunction (LUTD) using quantitative symptomatic scoring or objective parameters evaluated by uroflowmetry.
Objective: To clarify the effect of tiotropium on lower urinary tract functions in COPD patients with BPH.
Methods: This prospective pilot study comprised 25 male COPD patients with BPH as defined by the International Prostate Symptom Score (IPSS), the quality of life (QOL) index, maximum flow rate (Q-max) in uroflowmetry, and prostate volume. Patients were given tiotropium once a day for 3 months. At baseline and after treatment, lower urinary tract functions were assessed symptomatically by the IPSS and the QOL index, and objectively by urinary parameters, including Q-max, average flow rate (Q-ave), postvoid residual urine volume (PVR), and bladder voiding efficiency (BVE).
Results: Acute urinary retention was not observed in any patients. Subjectively, no significant difference was found in the IPSS or the QOL index between baseline and after tiotropium treatment. Additionally, tiotropium treatment did not change Q-max, Q-ave, time to Q-max, or overall flow time compared to baseline (Q-max (mL/s), 9.66+/-3.63, 9.11+/-3.68 and 10.51+/-3.88, P=0.15; Q-ave (mL/s), 4.20+/-1.76, 4.14+/-1.55, and 4.71+/-1.81, P=0.31; time to Q-max (s), 12.1+/-8.0, 16.2+/-11.4, and 13.0+/-11.3, P=0.10; flow time (s), 39.4+/-19.6, 40.4+/-20.1, and 38.3+/-19.1; baseline, 1 month after treatment and 3 months after treatment, respectively). No significant increase was found in PVR or BVE (PVR (mL), 57.9+/-51.2, 55.4+/-47.2 and 66.1+/-52.7, P=0.36; BVE (%), 75.8+/-18.4, 73.3+/-19.1 and 73.9+/-17.3, P=0.67; baseline, 1 month after treatment, and 3 months after treatment, respectively).
Conclusion: In our preliminary study, tiotropium did not adversely affect lower urinary tract functions in COPD patients with BPH, suggesting the possibility that tiotropium can be safely given to those patients. This warrants future studies in a larger series of COPD patients to validate our observations.