Factorial validity and invariance of the Patient Health Questionnaire (PHQ)-9 among clinical and non-clinical populations

PLoS One. 2018 Jul 19;13(7):e0199235. doi: 10.1371/journal.pone.0199235. eCollection 2018.

Abstract

The Patient Health Questionnaire-9 (PHQ-9) is commonly used to screen for depressive disorder and for monitoring depressive symptoms. However, there are mixed findings regarding its factor structure (i.e., whether it has a unidimensional, two-dimensional, or bi-factor structure). Furthermore, its measurement invariance between non-clinical and clinical populations and that between patients with major depressive disorder (MDD) and MDD with comorbid anxiety disorder (AD) is unknown. Japanese adults with MDD (n = 406), MDD with AD (n = 636), and no psychiatric disorders (non-clinical population; n = 1,163) answered this questionnaire on the Internet. Confirmatory factor analyses showed that the bi-factor model had a better fit than the unidimensional and two-dimensional factor models did. The results of a multi-group confirmatory factor analysis indicated scalar invariance between the non-clinical and only MDD groups, and that between the only MDD and MDD with AD groups. In conclusion, the bi-factor model with two specific factors was supported among the non-clinical, only MDD, and MDD with AD groups. The scalar measurement invariance model was supported between the groups, which indicated the total or sub-scale scores were comparable between groups.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Anxiety Disorders / diagnosis
  • Anxiety Disorders / epidemiology*
  • Anxiety Disorders / physiopathology
  • Comorbidity
  • Depressive Disorder, Major / diagnosis
  • Depressive Disorder, Major / epidemiology*
  • Depressive Disorder, Major / physiopathology
  • Factor Analysis, Statistical
  • Female
  • Humans
  • Internet
  • Japan / epidemiology
  • Male
  • Middle Aged
  • Patient Health Questionnaire / statistics & numerical data*
  • Psychiatric Status Rating Scales / statistics & numerical data*
  • Psychometrics

Grants and funding

The current study was supported by a Grant-in-Aid for Research Activity start-up (24830127, http://www.jsps.go.jp/english/e-grants/index.html) awarded to MI from the Japan Society for the Promotion of Science, National Center of Neurology and Psychiatry Intramural Research Grant (24-4, http://www.ncnp.go.jp/guide/cost.html) for Neurological and Psychiatric Disorders. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.