title: A 4-item measure of depression and anxiety: validation and standardization of the Patient Health Questionnaire-4 (PHQ-4) in the general population.
abstract: BACKGROUND
  The 4-item Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief self-report questionnaire that consists of a 2-item depression scale (PHQ-2) and a 2-item anxiety scale (GAD-2). Given that PHQ-4, PHQ-2, and GAD-2 have not been validated in the general population, this study aimed to investigate their reliability and validity in a large general population sample and to generate normative data.
  
  
  METHODS
  A nationally representative face-to-face household survey was conducted in Germany in 2006. The survey questionnaire consisted of the PHQ-4, other self-report instruments, and demographic characteristics.
  
  
  RESULTS
  Of the 5030 participants (response rate=72.9%), 53.6% were female and mean (SD) age was 48.4 (18.0) years. The sociodemographic characteristics of the study sample closely match those of the total populations in Germany as well as those in the United States. Confirmatory factor analyses showed very good fit indices for a two-factor solution (RMSEA .027; 90% CI .023-.032). All models tested were structurally invariant between different age and gender groups. Construct validity of the PHQ-4, PHQ-2, and GAD-2 was supported by intercorrelations with other self-report scales and with demographic risk factors for depression and anxiety. PHQ-2 and GAD-2 scores of 3 corresponded to percentile ranks of 93.4% and 95.2%, respectively, whereas PHQ-2 and GAD-2 scores of 5 corresponded to percentile ranks of 99.0% and 99.2%, respectively.
  
  
  CONCLUSIONS
  A criterion standard diagnostic interview for depression and anxiety was not included.
  
  
  CONCLUSIONS
  Results from this study support the reliability and validity of the PHQ-4, PHQ-2, and GAD-2 as ultra-brief measures of depression and anxiety in the general population. The normative data provided in this study can be used to compare a subject's scale score with those determined from a general population reference group.
authors.affiliation: Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Hamburg-Eppendorf and Hamburg-Eilbek (Schön Clinics), 20246 Hamburg, Germany. b.loewe@uke.de
authors.forename: Bernd
authors.initials: B
authors.lastname: Löwe
authors.forename: Inka
authors.initials: I
authors.lastname: Wahl
authors.forename: Matthias
authors.initials: M
authors.lastname: Rose
authors.forename: Carsten
authors.initials: C
authors.lastname: Spitzer
authors.forename: Heide
authors.initials: H
authors.lastname: Glaesmer
authors.forename: Katja
authors.initials: K
authors.lastname: Wingenfeld
authors.forename: Antonius
authors.initials: A
authors.lastname: Schneider
authors.forename: Elmar
authors.initials: E
authors.lastname: Brähler
mesh_terms: D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D005260:Female; D005858:Germany; D006306:Health Surveys; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires