The Kessler Psychological Distress Scale (K10)

Description
The K10 is a psychological screening tool designed to identify adults with significant levels of psychological distress so that they may be appropriately managed. It has been widely used in the United States as well as in Australia, where it has been included in the Australian Survey of Mental Health and Wellbeing (1997) and the Australian National Health Surveys.

Validity
It has been validated for use by Professor Gavin Andrews and research has revealed a strong association between high scores on the K10 and a current CIDI (WHO Composite International Diagnostic Interview) diagnosis of anxiety and affective disorders. There is a lesser but significant association between the K10 and other mental disorder categories and with the presence of any current mental disorder (Andrews & Slade, 2001). Sensitivity and specificity data analysis also supports the K10 as an appropriate screening instrument to identify likely cases of anxiety and depression in the community and to monitor treatment outcomes.

Interpretation
Scores range from 10 to 50 with higher scores indicating a greater likelihood of having a mental disorder, or a higher severity of psychological distress. Scores can be split into four main categories. People seen in primary care who score;
under 20 are likely to be psychologically well,
20-24 are likely to have a mild mental disorder,
25-29 are likely to have moderate mental disorder,
30 and over are likely to have a severe mental disorder.

13% of the adult population will score 20 and over and approximately 25% of patients seen in primary care will score 20 and over. This is a screening instrument and practitioners should make a clinical judgment as to whether a person is distressed. Scores usually decline with psychological treatment. Patients whose scores remain above 24 after treatment should be reviewed.

Developer
The scale was developed in 1992 by Kessler for use in population surveys.