01-11-2011 | Uitgave 9/2011
Development and psychometric evaluation of a new patient-reported outcome instrument measuring the functional impact of insomnia
- Tijdschrift:
- Quality of Life Research > Uitgave 9/2011
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Electronic supplementary material
The online version of this article (doi:10.1007/s11136-011-9885-8) contains supplementary material, which is available to authorized users.
Disclaimer: Funding for this study was provided by GlaxoSmithKline, Research Triangle Park, NC. All listed authors meet the criteria for authorship set forth by the International Committee for Medical Journal Editors.
Abstract
Purpose
The objective of this study was to develop and validate a patient-reported outcome instrument to comprehensively assess the consequences of inadequate sleep for use in insomnia-related studies.
Methods
To inform item development, relevant constructs were identified through patient focus groups, literature review, and expert input. Following a translatability assessment for United States (US) English, US Spanish, and French, the draft items were refined through iterative sets of patient interviews in the United States and France. Psychometric properties were evaluated using patient responses from a validation study including 432 participants with either a diagnosis of primary insomnia or no history of insomnia.
Results
Psychometric analyses supported item reduction from 38 to 26 items, yielding a unidimensional scale and preserving the original content (mood, tiredness/energy, memory/concentration, motivation, daily performance, social interaction, sexual functioning). Evidence of internal consistency (coefficient α = 0.97), convergent validity, and known-groups validity also was documented.
Conclusions
The Sleep Functional Impact Scale (SFIS) is a psychometrically sound measure targeting the impact of insomnia on patient functioning. When administered with a sleep diary, this instrument has the ability to provide a more comprehensive assessment of treatment response in clinical studies.