K10: Kessler Psychological Distress Scale, 10-item version

What this assessment is

The K10 measures nonspecific psychological distress with 10 items. It records how often a person experienced several forms of emotional distress during a recent period.

Ronald Kessler and colleagues developed it for population health surveys. The six-item K6 is a short form made from six of the K10 questions.

The result is broad. One total summarizes several forms of distress, but it does not identify a condition or explain what caused the distress.

Who it was designed for

The K10 was developed for general population research. National surveys in Australia, Canada, and other countries have used it to compare levels of distress across groups.

The original development study tested the K10 in population surveys and a clinical reappraisal sample. Its purpose was efficient screening and population measurement, not diagnosis by questionnaire.

Comparisons need consistency. A useful comparison keeps the scoring system, timeframe, language, and administration method the same because each feature can affect the result.

How it is administered

The developer provides self-administered and interviewer-administered English forms. The standard developer form asks about the past 30 days and uses five frequency choices.

Australian surveys often say the previous four weeks. The 2020 to 2022 Australian national study used that wording and noted the difference from its earlier 30-day form.

Some K10+ forms add questions about persistence, functioning, healthcare use, and physical causes. Those extra questions do not contribute to the K10 total.

What it measures

The K10 measures broad distress in the anxiety and depression spectrum. It covers emotional and physical experiences associated with distress without assigning them to one diagnosis.

The total cannot identify why someone feels distressed. It also cannot show how much a specific problem affects work, relationships, self-care, or safety unless those topics are assessed separately.

How scoring works

Start with the score range. Two common coding systems produce different totals from the same 10 responses.

• The developer's method assigns 0 to 4 points per response. The total runs from 0 to 40.
• The Australian method assigns 1 to 5 points per response. The total runs from 10 to 50.

The developer's scoring guide describes both methods. A 10 to 50 total is exactly 10 points higher than the matching 0 to 40 total.

Higher totals indicate more frequent psychological distress in both systems. That part does not change.

The number does change. Scores should not be compared until the coding method is known, because matching responses differ by 10 points across the two systems.

Do not mix them.

Missing responses also need a stated rule. The developer does not prescribe one method for every use. Some Australian reporting systems require all 10 responses before calculating a total.

How to interpret a K10 score

There are no universal K10 severity bands. Bands need a source. Even Australian government systems divide the 10 to 50 range in different ways.

The Australian Bureau of Statistics has used these groups:

• 10 to 15: low
• 16 to 21: moderate
• 22 to 29: high
• 30 to 50: very high

Another Australian government metadata standard uses:

• 10 to 19: low
• 20 to 24: mild
• 25 to 29: moderate
• 30 to 50: severe

The Australian Institute of Health and Welfare warns that different groupings are used across surveys and research. The labels are reporting conventions tied to a method and population.

A K10 score is not a diagnosis. No band can confirm depression, an anxiety disorder, or serious mental illness. A clinical assessment is needed to determine whether a condition is present.

What the score cannot tell you

The total does not identify a cause or a specific disorder. It cannot decide whether someone needs medication, therapy, urgent care, or no care.

That decision needs context.

A low score does not rule out a condition. Symptoms can be controlled by treatment, fall outside the recall period, or appear in ways the K10 does not measure.

Context comes first. A high score supports a closer look at current symptoms and functioning, considered with the person's history, circumstances, and concerns.

Evidence and limitations

The K10 was designed to measure distress efficiently in large surveys. The development research found strong performance for distinguishing likely cases from non-cases in the studied samples.

Its breadth is also a limit. One total combines several forms of distress and does not show which experiences drove the result.

Version details matter. A report should name the score range, timeframe, language, missing-response rule, and reference population before applying comparison bands.