The mediating role of sleep quality in the association between nocturia and health-related quality of life

BACKGROUND: Even though the negative impacts of nocturia on sleep quality and health-related quality of life (HRQOL) have been documented in previous research, their interrelationship has been poorly studied. This study aimed to explore whether nocturia would affect sleep quality, which in turn affects HRQOL. METHODS: Participants aged 40 and above were randomly recruited from a Hong Kong public primary care clinic. Participants were asked to report the average number of nocturia (waking up at night to void) pisodes per night over a 1-month period. The Pittsburgh Sleep Quality Index (PSQI) and the 12-Item Short Form Health Survey version 2 (SF-12 v2) were administered. The mediation analysis was tested using multistage regression approach and bootstrap method. RESULTS: Of the 500 subjects who completed the survey, 31.2% reported symptomatic nocturia (having ≥2 nocturia episodes per night), and 60.4% experienced poor sleep quality (a PSQI global score > 5). Respondents with symptomatic nocturia had a poorer HRQOL in the domains of physical functioning (PF), role physical (RP) and social functioning (SF), general health (GH), vitality (VT) and physical component summary (PCS) of the SF-12 v2 than those without. Compared with the respondents without poor sleep quality, those with poor sleep quality had poorer HRQOL across all domains and summaries of the SF-12 v2. Mediation analysis found that sleep quality fully mediated the association between nocturia and the PF, RP and SF domains of the SF-12 v2, respectively, and partially mediated the association between nocturia and the GH, VT and PCS domains of the SF-12 v2, respectively. CONCLUSIONS: We found that sleep quality mediated the association between nocturia and HRQOL. To enhance the HRQOL of patients with nocturia, clinicians should not only focus on nocturia symptoms, but also on their sleep quality.