Rationale, design, and methods of electroencephalography-based investigation of the effects of oral desmopressin on improving slow-wave sleep time in nocturnal polyuria patients (the DISTINCT study): protocol for a single-arm, open-label, single-assignment trial

BACKGROUND: Nocturia is one of the most bothersome lower urinary tract symptoms and often impairs sleep quality in the elderly. Although previous studies on nocturia have indicated that the successful treatment of nocturia improves sleep quality, most used questionnaires and activity devices to analyze sleep/wake patterns. Therefore, there is little information about the treatment effects of desmopressin on objective sleep quality. The aim of the DISTINCT study is to investigate the change in subjective and objective sleep quality using electroencephalography (EEG) and the Pittsburgh Sleep Quality Index (PSQI) after the administration of desmopressin in patients with nocturia due to nocturnal polyuria. METHODS: A total of 20 male patients, ≥65 years old, with nocturnal polyuria, defined as a nocturnal polyuria index (NPi) (nocturnal urine volume / 24 h urine volume) value ≥0.33, will participate in this study. The participants must have a nocturnal frequency of ≥2 and the first uninterrupted sleep period (FUSP) must occur within < 2.5 h. Desmopressin 50 μg per day will be orally administered before going to bed for 4 weeks. Urinary frequency volume charts (FVC) and EEG will be recorded prior to treatment and at 1 week and 4 weeks after the initiation of treatment. The PSQI will be completed before and 4 weeks after treatment. The primary endpoint is the change from baseline in the mean time of slow-wave sleep (sleep stages N3 and N4) at 4 weeks. The secondary endpoints include the change in the mean value of each sleep variable, the mean delta power during the FUSP, the correlation between nocturnal urinary frequency and slow-wave sleep time, and the change in PSQI score before and after treatment. DISCUSSION: The DISTINCT study will provide valuable evidence to indicate that oral desmopressin treatment for nocturnal polyuria prolongs the FUSP, resulting in the extension of slow-wave sleep time associated with sleep quality. TRIAL REGISTRATION: The Japan Registry of Clinical Trials (jRCTs051190080). Registered 9 December, 2019.