The Nightmare Quality of Life Questionnaire

Rationale Patient-centered outcomes are increasingly sought to evaluate social interactions and healthcare interventions in patients with sleep disorders. Yet, measures to assess quality of life (QoL) are lacking for those who experience nightmares. Objective The aim of the study is to describe the development and validation of a new health-related quality of life (HRQoL) instrument for patients with nightmares. Methods Attributes obtained from a focus group of patients (n = 113) with established nightmares were analyzed using exploratory factor analysis to elicit salient QoL themes for the new instrument. A validation cohort (n = 34) was used to determine the psychometric performance of the 16-item questionnaire including item-scaling, concurrent validity, and test-retest reliability tested four weeks apart. Results Four factors (sleep health, emotional and psychological well-being, social interaction, and motivation) explained 53.9% of the total variance. The Nightmare Quality of Life (NQoL) showed good internal consistency (Cronbach's alpha 0.85) and test-retest reliability (ICC = 0.89). Concurrent validity was evidenced by a strong correlation with the Nightmare Distress Questionnaire (r = 0.87; p < .001) and more modest associations with the Nightmare Frequency Questionnaire (r = , 0.69; p < .001), SF-36 (r = -0.68; p < .001), and PSQI (r = 0.45; p = .007). Conclusions The NQoL has demonstrable construct validity and reliability and represents a promising multi-dimensional instrument to assess outcome measures for quality of life in patients with nightmares.