Development of the Nocturia Sleep Quality Scale: a patient-reported outcome measure of sleep impact related to nocturia

Background/objective: Nocturia's impact on sleep causes significant burden for patients. This study aimed to develop a novel patient-reported outcome (PRO) measure, the Nocturia Sleep Quality Scale (NSQS), for the assessment of the impact of nocturia (defined as ≥2 nocturnal voids/night) on sleep.

Methods: Sleep-related concepts were identified through a targeted literature review, after which in-depth concept elicitation interviews with patients with a clinical diagnosis of nocturia were conducted. Draft items were generated to address concepts identified as important, meaningful, and relevant. Items were further refined through three iterative sets of cognitive debriefing interviews to optimize instructions, question wording, and response options. Two sleep research experts also provided input.

Results: The literature review and data from 18 concept elicitation interviews provided the basis for a comprehensive set of concepts. Constant comparative analysis was used to identify themes and support item development. The draft questionnaire consisted of 14 items with item-specific response scales. Wording and scaling of the items was optimized based on feedback from the 22 cognitive debriefing interviews and expert input. The results confirmed the completeness and relevance of the NSQS, providing support for the content validity and ability of items to reflect patient perception of nocturia-related sleep impacts.

Conclusions: The 6-item NSQS assesses the impact of nocturia on sleep by evaluating nighttime awakenings, sleep quantity, and sleep quality. The NSQS is self-administered and is intended to assess change in nocturia's impact on sleep after treatment in a standardized manner. Psychometric evaluation is under way to describe key measurement properties.