What is the K6 Distress Scale?

The K6 Psychological Distress Scale is a 6-item self-report questionnaire measuring non-specific psychological distress over the past 30 days. Developed by Ronald Kessler et al. (Arch Gen Psychiatry 2003) for the WHO World Mental Health Survey, K6 is the primary psychological distress measure in US national health surveys (NHANES, BRFSS, NSDUH) and used globally in population health surveillance.

What are the 6 K6 items?

K6 items assess past 30 days: (1) How often did you feel nervous? (2) How often did you feel hopeless? (3) How often did you feel restless or fidgety? (4) How often did you feel so depressed that nothing could cheer you up? (5) How often did you feel that everything was an effort? (6) How often did you feel worthless? Each rated 0-4 (None of the time to All of the time).

Can K6 be used for depression screening?

K6 provides non-specific distress screening, not depression-specific screening. While K6 correlates significantly with PHQ-9 (r approximately 0.70), it cannot identify whether distress is primarily depressive, anxious, or related to another condition. For depression-specific screening, PHQ-2 (2 items) or PHQ-9 are preferred. K6 is best used as a population triage layer, with disorder-specific tools applied to K6-positive cases.

What are K6 population norms in the US?

US adult population distribution (NHANES and NSDUH data): approximately 80% score 0-7 (no significant distress), 13-15% score 8-12 (mild-moderate distress), 3-4% score 13+ (serious psychological distress/SPD). The SPD prevalence varies by demographic: higher in women, younger adults, lower income groups, and racial/ethnic minority populations facing structural inequities.

Is K6 validated for adolescents?

Yes — K6 has been validated for adolescents aged 14-17 in US and international studies, including the National Longitudinal Study of Adolescent to Adult Health. This validation in adolescents distinguishes K6 from K10, which was primarily validated in adult populations. K6 cutoffs for adolescents mirror adult cutoffs (13+ for serious distress), though developmental context should inform clinical interpretation.

What are the clinical implications of a K6 score of 13 or higher?

K6 13+ (serious psychological distress) clinical implications: significantly increased risk of psychiatric emergency department visits, higher rates of suicidal ideation and attempts, greater functional impairment and disability days, higher healthcare utilization, and increased mortality risk (Dingfelder et al. 2011). Clinical response should include: disorder-specific assessment (PHQ-9, GAD-7), suicide risk assessment, and appropriate mental health referral.

How does K6 compare to PHQ-9 for mental health screening?

K6 vs PHQ-9: K6 is 6 items measuring non-specific distress (0-24 range, population surveillance optimized). PHQ-9 is 9 items measuring depression-specific symptoms (0-27 range, clinical assessment optimized). K6 is more efficient for population screening; PHQ-9 provides richer clinical information for individual patients. For primary care, PHQ-9 is preferred because it includes suicidal ideation assessment (item 9) and provides severity staging for treatment planning.

What languages is K6 available in?

K6 is available in numerous languages as part of the WHO World Mental Health Survey Initiative, including Spanish, French, German, Dutch, Chinese (Traditional and Simplified), Japanese, Korean, Arabic, Turkish, Portuguese, Italian, Polish, Russian, and many others. K6 translations are freely available from the World Mental Health Survey Consortium and have been validated for cross-cultural equivalence in most major language versions.

Online Medical Tools — K6 Scale

Printed on 9/3/2026

For informational purposes only. This is not medical advice.

Mental Health

K6 Scale

K6 is a concise population-level distress screen that estimates non-specific severe psychological distress risk over the past month.

Formula: K6 total = sum of 6 items scored 0-4 (range 0-24).

Felt nervous

Felt hopeless

Felt restless or fidgety

Felt so depressed nothing could cheer you up

Felt that everything was an effort

Felt worthless

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How It Works

Rate 6 Emotional Distress Items for the Past 30 Days

The patient rates 6 items about past 30-day emotional distress on a 0-4 scale: 0 = None of the time, 1 = A little of the time, 2 = Some of the time, 3 = Most of the time, 4 = All of the time. Items cover feeling nervous, hopeless, restless, depressed, worthless, and experiencing everything as an effort.

Sum All Items for Total Score 0-24

Sum all 6 items for a total score of 0-24. No reverse scoring required. Higher scores indicate greater psychological distress. K6 minimum is 0 (unlike K10 which starts at 10) because the response scale begins at 0 (None of the time).

Apply US Public Health Cutoffs

US SAMHSA and NHANES use cutoffs: 0-7 = no distress; 8-12 = mild to moderate distress; 13-24 = serious psychological distress (SPD). The threshold of 13+ is the standard US public health definition of serious psychological distress used in national health surveillance and SAMHSA reporting.

Who Uses the K6 Scale

US National Health Surveys and Epidemiology

Epidemiologists and Public Health Researchers

K6 is the primary psychological distress measure in major US national health surveys including NHANES (National Health and Nutrition Examination Survey), BRFSS (Behavioral Risk Factor Surveillance System), and NSDUH (National Survey on Drug Use and Health). K6 data enables tracking of serious psychological distress prevalence at state and national levels.

SAMHSA National Survey Implementation

SAMHSA Researchers and Health Policy Analysts

SAMHSA's National Survey on Drug Use and Health (NSDUH) uses K6 as the primary measure for identifying adults with serious mental illness (SMI) and serious psychological distress (SPD) at the national level. K6 13+ is the operational definition of SPD used in all SAMHSA national mental health estimates and policy reports.

State-Level Mental Health Surveillance

State Public Health Departments

K6 is used in BRFSS state-level health surveys to estimate serious psychological distress prevalence at state and county levels. This data is used by state health departments to allocate mental health resources, identify geographic disparities in mental health burden, and evaluate the impact of public mental health policies and programs.

Primary Care Brief Population Screen

Primary Care Physicians

K6 provides a 6-item, under-2-minute distress screen suitable for busy primary care settings. While K10 is preferred in Australian primary care, K6 is used in US primary care settings, particularly in federally qualified health centers (FQHCs) and safety-net clinics implementing population health mental health screening programs.

WHO World Mental Health Survey

International Mental Health Researchers

K6 is used in the WHO World Mental Health Survey Initiative across 30+ countries as the standard non-specific psychological distress measure for cross-national comparisons. Its 6-item brevity minimizes survey fatigue in large-scale international studies while providing reliable identification of serious psychological distress across diverse cultural contexts.

Refugee and Disaster-Affected Population Screening

NGOs and Humanitarian Health Workers

K6 has been validated in refugee and disaster-affected populations across multiple languages and cultures. It provides a standardized, brief distress measure for populations where access to mental health assessment is limited and where the direct consequences of distress (impaired functioning, suicide risk) require urgent identification.

Pro Tips

K6 Is the 6-Item Version of K10 — Both by Kessler et al.

K6 and K10 were both developed by Ronald Kessler and colleagues for the WHO World Mental Health Survey. K6 uses a 0-4 response scale (range 0-24) while K10 uses a 1-5 scale (range 10-50). K6 is the 6 highest-loading items from K10, optimized for ultra-brief population surveillance rather than detailed clinical assessment.

K6 Threshold of 13+ Is the SAMHSA Definition of Serious Psychological Distress

SAMHSA uses K6 13+ as the operational definition of serious psychological distress (SPD) in all national mental health prevalence estimates. Approximately 3% of US adults score 13+ on K6 annually. This threshold has sensitivity 0.36 and specificity 0.97 for serious mental illness — optimized for high specificity in population surveillance rather than clinical sensitivity.

K6 Has High Specificity (0.97) But Low Sensitivity (0.36) for Serious Mental Illness

K6 is designed for population surveillance, not clinical sensitivity. At threshold 13: specificity 0.97 means most K6-positive individuals do have serious mental illness — K6 positive screens are high-yield for clinical intervention. Sensitivity 0.36 means K6 misses approximately 64% of serious mental illness cases — K6 is not suitable as a comprehensive clinical screen for individuals.

K6 Is Used in US National Surveys; K10 Is Standard in Australian Primary Care

In US mental health epidemiology, K6 is the dominant tool (NHANES, BRFSS, NSDUH). In Australian primary care, K10 is mandated by Medicare Better Access. K6 data enables US national SMI prevalence estimates; K10 enables Australian individual patient severity tracking. Understanding which standard applies to your clinical or research context is essential for accurate interpretation.

K6 Is Validated for Adolescents — Unlike K10

K6 has been validated for use in adolescents aged 14-17, unlike K10 which was primarily developed for adults. K6 is used in adolescent health surveys including the National Longitudinal Study of Adolescent to Adult Health. This makes K6 particularly valuable for school-based or community screening of adolescent mental health.

K6 13+ Predicts Emergency Department Utilization and Suicide Risk

K6 13+ is associated with: significantly increased emergency department utilization for mental health crises, higher rates of suicidal ideation and attempts, greater disability and work impairment, higher healthcare costs, and increased mortality risk. Clinical follow-up of K6-positive patients should always include suicide risk assessment in addition to disorder-specific evaluation.

K6 Is Available Copyright-Free in Multiple Languages

K6 is freely available for research and clinical use without licensing fees. Official validated translations are available in Spanish, French, Chinese, Japanese, Korean, Arabic, and many others from the World Mental Health Survey Initiative. K6's free availability and brief format make it one of the most practical global psychological distress screening tools.

K6 Score Varies Systematically by Demographic Group

US population studies show K6 scores are higher in women than men, in younger adults than older adults, in lower socioeconomic status groups, in unemployed versus employed individuals, and in racial/ethnic minority groups facing structural discrimination. Demographic context should inform clinical interpretation of K6 scores and referral decisions.

Common Questions About Your Results

K6 and K10 have entirely different scoring ranges and clinical cutoffs. K6: 0-24 scale, serious distress threshold = 13+. K10: 10-50 scale, severe distress threshold = 30+. Applying K6 cutoffs to K10 scores (or vice versa) produces completely invalid interpretations. Always confirm which scale was administered before applying cutoffs. The different response formats (0-4 for K6 vs 1-5 for K10) also produce different distributions, preventing direct score comparison.

No. K6 measures non-specific psychological distress and cannot diagnose any specific disorder. K6 13+ indicates serious psychological distress that may reflect depression, anxiety, bipolar disorder, psychosis, PTSD, substance use disorder, or other conditions. All K6-positive screens require clinical follow-up with disorder-specific assessment tools (PHQ-9, GAD-7, AUDIT) and structured diagnostic interview.

K6 was designed primarily for population-level surveillance, not individual clinical decision-making. Its low sensitivity (0.36) means it misses most serious mental illness cases in individual patients. For individual clinical screening, K10 (10 items) or disorder-specific tools (PHQ-9, GAD-7) provide better clinical sensitivity. K6's role in individual care is as a rapid triage layer identifying highest-risk patients requiring immediate clinical follow-up.

K6 shows some cross-cultural variation in item endorsement and normative distributions. Cultural factors including stigma, reporting bias, and different idioms of distress affect K6 scores independent of actual distress burden. The 13+ SPD threshold may not have the same predictive validity across all cultural contexts. In non-Western populations, cultural adaptation studies should guide threshold selection rather than applying US normative cutoffs directly.

Evidence-Based Methodology

K6 developed by Kessler et al. (Arch Gen Psychiatry 2003) from World Health Organization World Mental Health Survey. Internal consistency alpha 0.89. Sensitivity 0.36, specificity 0.97 at threshold 13 for serious mental illness (optimized for population surveillance). Used in US NHANES, BRFSS, NSDUH, and National Comorbidity Survey Replication. WHO World Mental Health Survey Initiative uses K6 across 30+ countries. Dingfelder et al. (Health Serv Res 2011): K6 13+ and emergency department visits.

Clinical Content Trust

Last reviewed:: April 21, 2026
Guideline version:: General evidence framework v2026.04
Source set version:: Primary-source set v1

How to Interpret Your Result

Higher K6 totals indicate greater distress burden and support more comprehensive mental-health assessment.

When to Use This Tool

Use for rapid distress triage in clinical intake, primary care, and wellness-screening contexts.

Limitations

K6 is non-specific and does not determine diagnosis, etiology, or acute safety status without direct clinical assessment.

For related assessments, see K10 Distress, PHQ-4 and HADS.

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.

Sources

Changelog

April 21, 2026 · trust-baseline
Clinical trust metadata enabled for this tool page with structured review/version fields.

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Frequently Asked Questions

K6 score 13+ is the standard threshold for serious psychological distress (SPD) in US national health surveillance. At this threshold: sensitivity 0.36, specificity 0.97 for serious mental illness. The high specificity (0.97) means most K6-positive individuals have a diagnosable serious mental health condition; the lower sensitivity (0.36) reflects K6's design optimization for population surveillance rather than individual clinical screening.

K6 is embedded in major US national surveys: NHANES (in-person interview, representative US sample), BRFSS (telephone survey, state-level data), NSDUH (household survey, substance use and mental health). K6 data from these surveys generates SAMHSA's annual estimates of serious mental illness (SMI) and serious psychological distress (SPD) prevalence at national and state levels, used for mental health policy and resource allocation.

K6 at threshold 13: sensitivity 0.36 (correctly identifies 36% of serious mental illness cases), specificity 0.97 (correctly identifies 97% of individuals without serious mental illness). K6 is optimized for high specificity for population surveillance — it reliably identifies true positives but misses most cases. This design trade-off is intentional for survey research; it should not be used as the sole clinical screening tool where high sensitivity is required.

Online Medical Tools — K6 Scale

K6 Scale

How It Works

Rate 6 Emotional Distress Items for the Past 30 Days

Sum All Items for Total Score 0-24

Apply US Public Health Cutoffs

Who Uses the K6 Scale

US National Health Surveys and Epidemiology

SAMHSA National Survey Implementation

State-Level Mental Health Surveillance

Primary Care Brief Population Screen

WHO World Mental Health Survey

Refugee and Disaster-Affected Population Screening

Pro Tips

K6 Is the 6-Item Version of K10 — Both by Kessler et al.

K6 Threshold of 13+ Is the SAMHSA Definition of Serious Psychological Distress

K6 Has High Specificity (0.97) But Low Sensitivity (0.36) for Serious Mental Illness

K6 Is Used in US National Surveys; K10 Is Standard in Australian Primary Care

K6 Is Validated for Adolescents — Unlike K10

K6 13+ Predicts Emergency Department Utilization and Suicide Risk

K6 Is Available Copyright-Free in Multiple Languages

K6 Score Varies Systematically by Demographic Group

Common Questions About Your Results

Evidence-Based Methodology

Clinical Content Trust

How to Interpret Your Result

When to Use This Tool

Limitations

Sources

Changelog

Related Tools

K10 Distress

PHQ-4

HADS

Further Reading

Mental Health Screening Guide: Depression, Anxiety, Substance Use, and Cognitive Assessment

Frequently Asked Questions