Comparison Between Alpha Blocker Monotherapy and 5ARI Monotherapy Following Combination Therapy in Benign Prostatic Hyperplasia (BPH)

• Changes in patients' symptom questionnaires : IPSS, ICIQ male LUTS [ Time Frame: from baseline to 12 months of treatment ] [ Designated as safety issue: No ]
• Changes in urodynamic parameters : maximal flow rate and PVR [ Time Frame: from baseline to 12 months of treatment ] [ Designated as safety issue: No ]
• change in finding of TRUS [ Time Frame: from baseline to 12 months of treatment ] [ Designated as safety issue: No ]
• Numeric Change and percent change in PSA [ Time Frame: from baseline to 12 months of treatment ] [ Designated as safety issue: No ]
• safety evaluation : incidence and severity of adverse events [ Time Frame: 12 months of treatment ] [ Designated as safety issue: Yes ]

This study is designed to investigate the comparison between alpha blocker monotherapy and 5-alpha-reductase inhibitor monotherapy following combination therapy in benign prostatic hyperplasia.

• Drug: combination therapy
  alpha blocker and 5-alpha-reductase inhibitor medication
• Drug: alpha blocker monotherapy
  alpha blocker monotherapy group
• Drug: 5 alpha reductase inhibitor monotherapy
  5 alpha reductase inhibitor monotherapy

• Experimental: combination group
  combination therapy of alpha blocker and 5-alpha-reductase inhibitor medication
  Intervention: Drug: combination therapy
• Active Comparator: alpha blocker group
  alpha blocker monotherapy
  Intervention: Drug: alpha blocker monotherapy
• Active Comparator: 5 ARI group
  5 alpha-reductase inhibitor group
  Intervention: Drug: 5 alpha reductase inhibitor monotherapy

Inclusion Criteria:

1. Male aged 45 years old and above (with no upper limit of age)
2. patients who underwent combination therapy of alpha blocker and 5 ARI for more than 9 months
3. IPSS ≤ 12
4. Ability and willingness to correctly complete the micturition diary and questionnaire
5. Capable of understanding and having signed the informed consent form after full discussion of the research nature of the treatment and its risks and benefits

Exclusion Criteria:

1. An anticholinergic or antidiuretic if started less than 3 months prior to screening
2. Patients who had surgical treatment due to LUTS
3. Patients with suspected neurogenic bladder disorder
4. Patients with cancer of any type including cancer of the prostate or bladder
5. Patients with urethral stricture or bladder neck contracture
6. Patients with suspicious chronic prostatitis/chronic pelvic pain syndrome
7. Acute bacterial prostatitis less than 6 months prior to screening
8. Symptomatic acute urinary tract infection (UTI) less than 1 months prior to screening
9. Patients who had underwent prostatic biopsy less than one month prior to screening
10. Patients who had unstable angina or cerebral vascular disease less than 6 months prior to screening