Development and validation of the Maugeri Sleep Quality and Distress Inventory (MaSQuDI-17)

OBJECTIVES: The aim of this study was to develop and validate a questionnaire designed to measure the impact of sleep impairment on emotional distress in patients with various sleep disorders. METHODS: Five experts created an item data-bank pertaining to sleep-related psychological symptoms and somatic perceptions. Fifty patients in two focus groups examined each item for: a) word clarity (indicating any ambiguity of interpretation) and b) appropriateness for the target population. This process permitted to identify 36 appropriate items. Classical Test Theory and Rasch Analysis were used to further refine the questionnaire, yielding the final 17-item set. Concurrent validation of the new scale was tested with the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and the Anxiety and Depression questionnaires. RESULTS: Starting from the initial item data-bank, a 17-item questionnaire, the Maugeri Sleep Quality and Distress Inventory (MaSQuDI–17), was produced. Parallel Analysis on the MaSQuDI–17 confirmed the presence of a single dimension; exploratory factor analysis showed salient loading for each item, explaining 58.7% of total variance. Item-remainder correlation ranged from 0.72 to 0.39 and Cronbach alpha was 0.896. Rasch analysis revealed satisfactory psychometric properties of the new scale: the rating structure performed according to expectations, model fit was good and no item dependencies emerged. The scale presented good convergent validity and scores significantly distinguished healthy subjects from OSAS or Insomnia or BSD (p < 0.001). CONCLUSIONS: MaSQuDI –17 shows good psychometric qualities, and can be used to assess the impact of sleep disorders such as Insomnia, OSAS, Central Hypersomnia and BSD on emotional stress.