The temporal stability of the Kessler Psychological Distress Scale

Abstract

ABSTRACT Objective: The ten-item Kessler Psychological Distress Scale (K10) was designed as a screening tool to identify mental illness in epidemiological surveys. In recent years, it has also been employed in treatment studies and clinical settings to measure changes in psychological distress. However, no study to date has validated this extended use of the K10 by examining its temporal stability. This was the aim of the current study. Method: The K10 was administered on two occasions to a treatment-seeking sample (n = 289) and a non-treatment seeking sample (n = 129). To investigate the K10’s temporal stability over a range of clinically relevant time periods, test-retest reliability estimates were computed for multiple time intervals from 1–2 weeks to 8–13 weeks in the treatment-seeking sample. Results: For the testing interval of 1–2 weeks, the K10 demonstrated sound test-retest reliability in the treatment-seeking sample (ICC = .89; r = .80) and in the non-treatment-seeking sample (ICC = .86; r = .76). Comparable estimates were observed for the longer testing intervals in the treatment-seeking sample (ICCs = .84–.90; rs = .72–.81). Conclusion: This study provides evidence demonstrating the temporal stability of the K10, and supports its continued implementation as an outcome measure in mental health research and treatment. Key Points What is already known about this topic: The Kessler-10 (K10) is widely used measure of psychological distress. It is a well-validated screener for mental illness used in epidemiological surveys. Although the K10 was not designed for assessing psychotherapy outcomes, it is now routinely used in this way. What this topic adds: To support the use of the K10 in psychotherapy evaluation, its test re-test reliability needs to be examined. The K10 demonstrated temporal stability over a variety of clinically relevant time intervals in treatment and non-treatment seeking samples. Our data support the use of the K10 as a means of assessing changes in psychological distress over time.