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Printed on 7/20/2026
For informational purposes only. This is not medical advice.
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).
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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 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).
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.
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 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 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 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.
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.
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.
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.
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 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.
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 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+ 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 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.
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.
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.
Higher K6 totals indicate greater distress burden and support more comprehensive mental-health assessment.
Use for rapid distress triage in clinical intake, primary care, and wellness-screening contexts.
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.
April 21, 2026 · trust-baseline
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