Reliability generalization meta-analysis of the Athens Insomnia Scale and its translations: Examining internal consistency and test-retest validity

The Athens Insomnia Scale (AIS) is a widely used self-report measure to evaluate insomnia symptoms based on the International Classification of Diseases criteria version 10 (ICD-10). Despite its extensive use in clinical and research settings, the reliability of the AIS has not been systematically investigated. This systematic review reports a reliability generalization meta-analysis study to assess the internal consistency and the test-retest reliability of the AIS across various populations and settings. A systematic literature search was conducted to identify studies reporting Cronbach's alpha and test-retest coefficients for the AIS. Pooled estimates of reliability, along with moderator analyses, were calculated. The AIS has an excellent internal consistency of 0.84 (95% CI: 0.81 to 0.86), and re-test reliability of 0.86 (95% CI: 0.80 to 0.92). The significant heterogeneity levels support the recommendation that future studies using the AIS include and discuss reliability estimates based on their own data.