The Psychometric Properties of the Kessler Psychological Distress Scale (K6) in an Epidemiological Sample of Canadian Youth - PubMed (original) (raw)

The Psychometric Properties of the Kessler Psychological Distress Scale (K6) in an Epidemiological Sample of Canadian Youth

Mark A Ferro. Can J Psychiatry. 2019 Sep.

Abstract

in English, French

Objective: This study (1) describes the distribution of Kessler Psychological Distress Scale (K6) scores in an epidemiological sample of youth, (2) reports its item correlations and internal consistency reliability, (3) tests for measurement invariance by age (youth vs. adults) and sex, and (4) examines its predictive power for past-year psychiatric disorders.

Method: Youth aged 15 to 19 years (n = 2010) and adults aged 20 to 64 years (n = 2010) from the Canadian Community Health Survey-Mental Health who completed the K6 were included. Past-year psychiatric disorders were measured using the World Health Organization Composite International Diagnostic Interview 3.0 (WHO-CIDI). Polychoric correlation matrices and ordinal reliability coefficients were calculated to assess internal consistency of the K6, and confirmatory factor analysis was used to test for measurement invariance. Area under the curves (AUCs) were computed to determine the extent to which the K6 predicted a positive screen on the WHO-CIDI.

Results: K6 scores showed a J-shaped distribution, with >50% of youth having scores ≤3. Item and total scores were higher for females versus males. Item correlations were robust (0.31-0.78) and internal consistency was high (α = 0.86). Full measurement invariance was demonstrated between youth and adults, as well as between male and female youth. The K6 was a strong predictor of major depressive episode (AUC = 0.848), generalized anxiety disorder (AUC = 0.847), and bipolar disorder (AUC = 0.853).

Conclusions: The K6 is a valid and reliable measure of psychological distress among youth. Its brevity and robust predictive power for psychiatric disorder confirm its utility in clinical and community settings to identify youth needing comprehensive psychiatric assessment.

Objectif :: Cette étude: (1) décrit la distribution des scores à l’échelle de détresse psychologique de Kessler (K6) dans un échantillon épidémiologique d’adolescents; (2) rend compte des corrélations de ses items et de la fiabilité de la cohérence interne; (3) vérifie l’invariance de la mesure selon l’âge (adolescents c. adultes) et le sexe; et (4) examine son pouvoir de prédiction des troubles psychiatriques de l’année précédente.

Méthode :: Des adolescents de 15 à 19 ans (n = 2010) et des adultes de 20 à 64 ans (n = 2010) de l’Enquête sur la santé dans les collectivités canadiennes–Santé mentale qui ont répondu à la K6 ont été inclus. Les troubles psychiatriques de l’année précédente ont été mesurés à l’aide de l’Entrevue composite diagnostique internationale de l’Organisation mondiale de la santé 3.0 (WHO-CIDI). Les matrices des corrélations polychoriques et les coefficients de fiabilité ordinaux ont été calculés pour évaluer la cohérence interne de la K6, et l’analyse factorielle confirmatoire a servi à vérifier l’invariance de la mesure. Les zones sous la courbe (ZSC) ont été calculées pour déterminer à quel degré la K6 prédisait un dépistage positif à la WHO-CIDI.

Résultats :: Les scores à la K6 présentaient une distribution en forme de J, et >50% des adolescents avaient des scores ≤3. Les scores des items et totaux étaient plus élevés chez les femmes que chez les hommes. Les corrélations des items étaient fortes (0,31-0,78) et la cohérence interne était élevée (α = 0,86). L’invariance complète de la mesure était démontrée entre les adolescents et les adultes, ainsi qu’entre les adolescents et les adolescentes. La K6 prédisait fortement l’épisode dépressif majeur (ZSC = 0,848), le trouble d’anxiété généralisée (ZSC = 0,847), et le trouble bipolaire (ZSC = 0,853).

Conclusions :: La K6 est une mesure valide et fiable de la détresse psychologique chez les adolescents. Sa concision et son fort pouvoir de prédiction des troubles psychiatriques en confirment l’utilité en milieu clinique et communautaire pour repérer les adolescents nécessitant une évaluation psychiatrique complète.

Keywords: adolescent; measurement; mental disorder; mental health; validity.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: This work was conducted using data collected by Statistics Canada. However, the analyses presented here were conducted by the author and the interpretations presented in this paper do not reflect the interpretations or opinions of Statistics Canada. Dr. Ferro serves on the editorial board of the Canadian Journal of Psychiatry.

Figures

Figure 1.

Figure 1.

Distribution and cumulative prevalence of K6 scores.

Figure 2.

Figure 2.

Receiver operating characteristic (ROC) curves for the K6 and past-year mental disorder (full sample). (A) Major depressive episode, (B) generalized anxiety disorder, (C) bipolar disorder, and (D) any mental disorder.

Figure 3.

Figure 3.

Receiver operating characteristic (ROC) curves for the K6 and past-year mental disorder (males). (A) Major depressive episode, (B) generalized anxiety disorder, (C) bipolar disorder, and (D) any mental disorder.

Figure 4.

Figure 4.

Receiver operating characteristic (ROC) curves for the K6 and past-year mental disorder (females). (A) Major depressive episode, (B) generalized anxiety disorder, (C) bipolar disorder, and (D) any mental disorder.

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References

    1. Kessler RC, Andrews G, Colpe LJ. et al. Short screening scales to monitor population prevalences and trends in non-specific psychological distress. Psychol Med. 2002;32(6):959–976. - PubMed
    1. Kessler RC, Green JG, Gruber MJ. et al. Screening for serious mental illness in the general population with the K6 screening scale: results from the WHO World Mental Health (WMH) survey initiative. Int J Methods Psychiatr Res. 2010;19(suppl 1):4–22. - PMC - PubMed
    1. Chan SM, Fung TCT. Reliability and validity of K10 and K6 in screening depressive symptoms in Hong Kong adolescents. Vulnerable Child Youth Stud. 2014;9:75–85.
    1. Green JG, Gruber MJ, Sampson NA. et al. Improving the K6 short scale to predict serious emotional disturbance in adolescents in the USA. Int J Methods Psychiatr Res. 2010;19(suppl 1):23–35. - PMC - PubMed
    1. Mewton L, Kessler RC, Slade T. et al. The psychometric properties of the Kessler Psychological Distress Scale (K6) in a general population sample of adolescents. Psychol Assess. 2016;28(10):1232–1242. - PubMed

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