title: An ultra-brief screening scale for anxiety and depression: the PHQ-4.
abstract: BACKGROUND
  The most common mental disorders in both outpatient settings and the general population are depression and anxiety, which frequently coexist. Both of these disorders are associated with considerable disability.
  
  
  OBJECTIVE
  When the disorders co-occur, the disability is even greater. Authors sought to test an ultra-brief screening tool for both.
  
  
  METHODS
  Validated two-item ultra-brief screeners for depression and anxiety were combined to constitute the Patient Health Questionnaire for Depression and Anxiety (the PHQ-4). Data were analyzed from 2,149 patients drawn from 15 primary-care clinics in the United States.
  
  
  RESULTS
  Factor analysis confirmed two discrete factors (Depression and Anxiety) that explained 84% of the total variance. Increasing PHQ-4 scores were strongly associated with functional impairment, disability days, and healthcare use. Anxiety had a substantial effect on functional status that was independent of depression.
  
  
  CONCLUSIONS
  The PHQ-4 is a valid ultra-brief tool for detecting both anxiety and depressive disorders.
authors.affiliation: Regenstrief Institute, Indianapolis, IN 46202, USA. kkroenke@regenstrief.org
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroenke
authors.forename: Robert L
authors.initials: RL
authors.lastname: Spitzer
authors.forename: Janet B W
authors.initials: JB
authors.lastname: Williams
authors.forename: Bernd
authors.initials: B
authors.lastname: Löwe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001008:Anxiety Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D015897:Comorbidity; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007406:Interview, Psychological / Q000379:methods; D008297:Male; D008403:Mass Screening / Q000379:methods* / Q000706:statistics & numerical data; D008603:Mental Health / Q000706:statistics & numerical data*; D008875:Middle Aged; D015995:Prevalence; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D012650:Self Disclosure; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult