K10 — Kessler Psychological Distress Scale (10 items)

Kessler and colleagues (2002) developed the K10 for the WHO World Mental Health surveys to screen for anxiety and depressive disorders in population research. The scale asks how often over the past four weeks the respondent has experienced symptoms of non-specific psychological distress — including nervousness, hopelessness, restlessness, worthlessness, and fatigue. Each of the 10 items is rated on a 5-point frequency scale from "none of the time" (1) to "all of the time" (5).

The total score (10–50) provides a continuous measure of distress severity. The K10 is not diagnostic — it identifies individuals with elevated distress who may warrant further clinical assessment. Its brevity and strong psychometric properties have made it a standard component of population health surveys, including the Australian National Survey of Mental Health and Wellbeing, and it is recommended by the Australian Bureau of Statistics for mental health monitoring.

Because all items use a frequency anchor (how often), the K10 captures state-level distress rather than the presence of specific symptoms, making it sensitive to change across time and useful for treatment monitoring alongside diagnostic tools.

Each item is scored 1 (none of the time) to 5 (all of the time); all 10 are summed with no reverse scoring. Total range is 10–50. Interpretation bands follow Andrews & Slade (2001): below 20 = likely well; 20–24 = mild distress; 25–29 = moderate distress; 30–50 = severe distress. These are population-derived descriptive bands, not diagnostic criteria.

The K10 is © World Health Organization. Free for clinical and research use; a commercial-use grey area applies — do not imply commercial clearance. Administered here with attribution.