Consistency as the Currency in Psychological Measures: A Reliability Generalization Meta-Analysis of Kessler Psychological Distress Scale (K-10 and K-6)

Abstract

Background: Psychological distress is a critical concern in mental health, significantly impacting the quality of life across lifespan. Reliable and culturally adaptable assessment tools are essential for effective diagnosis and intervention. The Kessler Psychological Distress Scales (K-10 and K-6) are widely used for their efficiency and psychometric strength, but the reliability of K-10 and K-6 across different populations and settings remains to be determined. Objective: This study aims to evaluate the reliability generalization (RG) of the K-10 and K-6 scales across diverse demographic and cultural contexts, providing a comprehensive meta-analysis of their performance. Method: A RG meta-analysis was conducted using data from peer-reviewed articles published between 2002 and 2024, sourced from databases such as Web of Science, Scopus, and ScienceDirect. The analysis included 48 studies that reported reliability measures like Cronbach’s α, focusing on the psychometric properties of the scales across various populations and settings. Results: The meta-analysis revealed high internal consistency for both the K-10 (mean α = 0.90, 95% confidence interval (CI) [0.88, 0.91]) and K-6 (mean α = 0.84, 95% CI [0.80, 0.88]) scales. Reliability varied across different populations and languages. For the K-10, the highest reliability was found among adolescents (α = 0.93) and carers (α = 0.91). The K-10 demonstrated exceptional reliability in settings such as Australia (α = 0.97) and significant variability in Tanzania (α = 0.78). The K-6 scale showed high reliability among outpatients (α = 0.89) and the general population (α = 0.87). The scales were adapted into multiple languages, including English, Chinese, Swahili, Farsi, Indonesian, Japanese, Hindi, and Portuguese, reflecting their global applicability and adaptability. Conclusion: The Kessler Psychological Distress Scales (K-10 and K-6) are reliable tools for measuring psychological distress in general and clinical populations. Their high reliability and adaptability across diverse settings highlight their value in clinical practice and research. These findings support the continued use and adaptation of these scales in global mental health assessments, emphasizing the importance of cultural and linguistic considerations.