A New Single-Item Sleep Quality Scale: Results of Psychometric Evaluation in Patients With Chronic Primary Insomnia and Depression.
Level 2 - randomized trial
Psychometric validation study embedded within prospective clinical trial cohorts.
PubMed 30373688 · doi:10.5664/jcsm.7478
What was done
Researchers evaluated the measurement properties of a newly developed single-item Sleep Quality Scale (SQS) against the Pittsburgh Sleep Quality Index (PSQI) and the morning questionnaire-insomnia (MQI). Data were analyzed from two clinical trial cohorts: 70 patients with chronic primary insomnia treated for 4 weeks with an FDA-approved hypnotic agent, and 651 patients with depression treated for 8 weeks with active or experimental therapy. Prespecified psychometric analyses assessed concurrent criterion validity, convergent/divergent construct validity, known-groups validity, test-retest reliability (intraclass correlation coefficient, ICC), and responsiveness (standardized response means, SRM).
What was found
Concurrent criterion validity was demonstrated by inverse correlations between the SQS and specific sleep quality items from the MQI at week 1 (Pearson r = -0.76) in insomnia patients, and the PSQI at week 8 (Goodman-Kruskal r = -0.92) in depressed patients. Test-retest reliability (ICC) was 0.62 over 4 weeks of sleep stability in insomnia and 0.74 over 1 week in stable depression. Responsiveness effect sizes (SRM) from baseline were 1.32 at week 1 in insomnia and 0.67 at week 8 in depression. Mean SQS scores differentiated between normal sleepers, borderline sleep problems, and those with sleep problems, and score changes corresponded with categories of PSQI improvement.
Why it matters
Comprehensive multi-item sleep questionnaires can be burdensome in routine practice and clinical trials. This single-item scale offers a practical, low-burden alternative that captures meaningful differences in sleep quality.
Limits
Analyses were conducted secondary to clinical trials rather than in a dedicated primary validation cohort. The sample size for the insomnia group was relatively small (n = 70), generalizability to other sleep disorders or healthy populations was not tested, and no objective sleep measurements (such as actigraphy or polysomnography) were reported.
Cited by
- contradicts The metric known as the Sleep Quality Index is FDA-approved and supported by substantial scientific validation.