The evaluation of nocturia in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia and the analysis of the curative effect after medical or placebo therapy for nocturia: a randomized placebo-controlled study

BACKGROUND: To study nocturia in patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) after medical or placebo treatment. METHODS: Patients with LUTS suggestive of BPH from several community clinics were included. Patients completed the International Prostate Symptom Score (I-PSS) questionnaire and a 3-day voiding diary. Urinalysis, prostate-specific antigen (PSA) measurement, and prostate ultrasonography were performed. Nocturnal polyuria (NP) was defined as a nocturnal urine fraction exceeding one third of the daily urine output in elderly men. A total of 148 outpatients were randomized to drug treatment (tamsulosin) or placebo treatment. After 8 weeks of treatment, they were re-evaluated using a 3-day voiding diary, PSA measurement, prostate volume (PV), I-PSS, etc. RESULTS: The average I-PSS score was 20.3, storage symptom score was 11.7, voiding symptom score was 8.6, quality of life (QoL) score was 3.7, PV was 40.4 ± 19.4 ml, and nocturnal urine volume (NUV) was 845.7 ± 339.0 ml. The mean frequency of nocturia was 2.3 ± 1.1 per day, and 94% of the patients had a nocturia frequency of more than two times per day. Of these patients, 76.5% had NP. A significant correlation was found between NUV and the amount of water intake at night and 4 h before sleep (r = 0.419,P = 0.002; r = 0.302,P = 0.031). Eighty patients were randomized to drug treatment (tamsulosin) and 68 patients were randomized to placebo treatment. The I-PSS score was 16.8 ± 4.9 to 19.3 ± 5.0 (p = 0.002), the storage symptom score was 10.3 ± 3.4 to 10.7 ± 3.4 (p = 0.007), and the voiding symptom score was 7.5 ± 2.4 to 8.6 ± 2.3 (p = 0.003). The frequency of daytime urination was 7.5 ± 2.6 to 8.1 ± 2.6 (p = 0.002), maximum urine volume (ml) was 372.8 ± 103.3 to 302.8 ± 119.3 (p = 0.007), and morning urine volume (ml) was 280.5 ± 111.7 to 259.5 ± 100.7 (p = 0.003). However, the frequency of nocturia score was 2.8 ± 0.7 to 3.0 ± 0.6 (p = 0.306) and the nocturnal urine volume (ml) was 800.7 ± 323.0 to 845.7 ± 303.5 (p = 0.056), which did not change significantly. There were significant differences between the NP and non-NP groups in the duration of LUTS, first voided urine volume, daytime urination frequency, and the amount of water intake at night and 4 h before sleep. CONCLUSIONS: Among the symptoms of LUTS, the improvement rates for nocturia were the lowest after medical treatment for BPH. The α-blockers did not improve nocturia, which was a common symptom accompanying LUTS suggestive of BPH. Our results showed that the prevalence of NP was 76.5% and that NP was significantly related to the amount of water intake during the evening and before sleep. TRIAL REGISTRATION: ISRCTN registry, Trial registration number (TRN): ISRCTN85509614, Date of registration: 30/10/2018. This trial was registered retrospectively.