Research report
The PHQ-8 as a measure of current depression in the general population

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Abstract

Background

The eight-item Patient Health Questionnaire depression scale (PHQ-8) is established as a valid diagnostic and severity measure for depressive disorders in large clinical studies. Our objectives were to assess the PHQ-8 as a depression measure in a large, epidemiological population-based study, and to determine the comparability of depression as defined by the PHQ-8 diagnostic algorithm vs. a PHQ-8 cutpoint ≥ 10.

Methods

Random-digit-dialed telephone survey of 198,678 participants in the 2006 Behavioral Risk Factor Surveillance Survey (BRFSS), a population-based survey in the United States. Current depression as defined by either the DSM-IV based diagnostic algorithm (i.e., major depressive or other depressive disorder) of the PHQ-8 or a PHQ-8 score ≥ 10; respondent sociodemographic characteristics; number of days of impairment in the past 30 days in multiple domains of health-related quality of life (HRQoL).

Results

The prevalence of current depression was similar whether defined by the diagnostic algorithm or a PHQ-8 score ≥ 10 (9.1% vs. 8.6%). Depressed patients had substantially more days of impairment across multiple domains of HRQoL, and the impairment was nearly identical in depressed groups defined by either method. Of the 17,040 respondents with a PHQ-8 score ≥ 10, major depressive disorder was present in 49.7%, other depressive disorder in 23.9%, depressed mood or anhedonia in another 22.8%, and no evidence of depressive disorder or depressive symptoms in only 3.5%.

Limitations

The PHQ-8 diagnostic algorithm rather than an independent structured psychiatric interview was used as the criterion standard.

Conclusions

The PHQ-8 is a useful depression measure for population-based studies, and either its diagnostic algorithm or a cutpoint ≥ 10 can be used for defining current depression.

Introduction

Depression is not only the most common mental disorder in general practice as well as mental health settings, but also is a major public health problem. The World Health Organization now recognizes depression as one of the most burdensome diseases in the world (World Health Organization, 2002). It is also among the leading causes of decreased work productivity (Stewart et al., 2003). The prevalence and impact of depression in the United States has been assessed in important population-based studies, with modern methods first used in the Epidemiological Catchment Area study in the early 1980s (Robins and Regier, 1991) and proceeding to the National Comorbidity Survey in 1990–1992 (Kessler et al., 1994) and its replication (NCS-R) a decade later (Kessler et al., 2003). Utilizing structured psychiatric interviews, these landmark epidemiological studies have provided invaluable information on the community prevalence of depression and other mental disorders.

However, there are a number of periodic population-based surveys conducted by federal or state agencies that provide an opportunity for more regular surveillance, although these surveys do not focus exclusively on depression or psychiatric conditions. Because mental health may be only one of a number of health indicators assessed, brief measures may be essential to reduce respondent burden. One increasingly popular measure for assessing depression is the Patient Health Questionnaire nine-item depression scale (PHQ-9). Since its original validation study in 2001 (Kroenke et al., 2001), the PHQ-9 already has been used in several hundred published studies and translated into more than 30 languages. It consists of the nine criteria for depression from the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV). The PHQ-9 is half the length of many depression measures, comparable or superior in operating characteristics, and valid as both a diagnostic and severity measure (Lowe et al., 2004a, Williams et al., 2002a, Williams et al., 2002b). It has been used in clinical (Diez-Quevedo et al., 2001, Kroenke and Spitzer, 2002) and population-based settings (Martin et al., 2006) and is valid in self-administered (Diez-Quevedo et al., 2001, Kroenke et al., 2001) and telephone-administered modes (Pinto-Meza et al., 2005). Additionally, the PHQ-9 is effective for detecting depressive symptoms in various racial/ethnic groups (Huang et al., 2006a, Huang et al., 2006b) and older populations (Klapow et al., 2002), as well as in patients with neurological disorders (Bombardier et al., 2006, Bombardier et al., 2004, Callahan et al., 2006, Fann et al., 2005, Williams et al., 2004, Williams et al., 2005), cardiovascular disease (Holzapfel et al., 2007, Ruo et al., 2003), HIV/AIDS (Justice et al., 2004), diabetes (Glasgow et al., 2004, Katon et al., 2004), chronic kidney disease (Drayer et al., 2006), cancer (Dwight-Johnson et al., 2005), rheumatological disorders (Lowe et al., 2004c, Rosemann et al., 2007), gastrointestinal disease (Persoons et al., 2001), dermatological disorders (Picardi et al., 2004), and other conditions (Lowe et al., 2004b, Maizels et al., 2006, Persoons et al., 2003, Scholle et al., 2003, Spitzer et al., 2000, Tietjen et al., 2007, Turner and Dworkin, 2004, Turvey et al., 2007).

In order to assess the current prevalence and impact of depression in the United States, an eight-item version of the Patient Health Questionnaire depression scale (PHQ-8) recently was made available for use by state health departments in the 2006 Behavioral Risk Factor Surveillance Survey (BRFSS). The PHQ-8 is comparable to the PHQ-9 in terms of diagnosing depressive disorders when using a DSM-IV based diagnostic algorithm (Corson et al., 2004, Kroenke and Spitzer, 2002). However, there is evidence that a PHQ-8 score ≥ 10 represents clinically significant depression (Kroenke et al., 2001) and is more convenient to use than a diagnostic algorithm. In this paper, we compare the standard diagnostic algorithm and the PHQ-8 cutpoint of 10 in terms of depression prevalence, respondent sociodemographic characteristics, PHQ-8 operating characteristics, and construct validity as assessed by multiple domains of health-related quality of life. Assessment of the PHQ-8 in this large, epidemiological study may provide further evidence of its utility as a depression measure in population-based research.

Section snippets

Behavioral Risk Factor Surveillance Survey (BRFSS)

The BRFSS is a surveillance system operated by state health departments in collaboration with CDC. It aims to collect uniform, state-specific data on preventive health practices and risk behaviors that are linked to chronic diseases, injuries, and preventable infectious diseases in the adult population (Centers for Disease Control and Prevention, 2005, Mokdad et al., 2003). Trained interviewers collect data from a standardized questionnaire using an independent probability sample of households

Respondent characteristics

Data were analyzed from 198,678 respondents to the 2006 BRFSS survey. Overall, the sample was 61.6% women, 78% non-Hispanic white, 58.3% currently employed, 61.2% college educated, and 56.9% currently married. A lifetime diagnosis of a depressive or anxiety disorder was reported by 18.0% and 12.3%, respectively.

Table 1 compares the characteristics of depressed vs. nondepressed respondents, with depression defined either by the PHQ-8 diagnostic algorithm (major depressive or other depressive

Discussion

BRFSS provided an excellent opportunity to examine the PHQ-8 in a large, representative study of the U.S. population. The two methods of estimating current depression – the validated PHQ-8 diagnostic algorithm based upon DSM-IV criteria, and a PHQ-8 cutpoint of 10 – yielded similar prevalences (9.1% and 8.6%, respectively). Also, sociodemographic characteristics were similar in the depressed and nondepressed groups defined by these two methods. Patients classified by the PHQ-8 as having current

Role of funding source

There was no external funding for this study.

Conflict of interest

The authors have no conflicts of interest with respect to this paper.

Acknowledgments

We thank the state health department personnel who collaborated with in the Centers for Disease Control and Prevention (CDC) and the Substance Abuse and Mental Health Services Administration (SAMHSA) on the implementation of the Anxiety and Depression Module for the Behavioral Risk Factor Surveillance System (BRFSS).

References (62)

  • SpitzerR.L. et al.

    Validity and utility of the Patient Health Questionnaire in assessment of 3000 obstetric-gynecologic patients: the PRIME-MD Patient Health Questionnaire Obstetrics-Gynecology Study

    Am. J. Obstet. Gynecol.

    (2000)
  • TurnerJ.A. et al.

    Screening for psychosocial risk factors in patients with chronic orofacial pain — recent advances

    J. Am. Dental Assoc.

    (2004)
  • WilliamsJ.W. et al.

    Identifying depression in primary care: a literature synthesis of case-finding instruments

    Gen. Hosp. Psychiatry

    (2002)
  • American Psychiatric Association

    Diagnostic and Statistical Manual of Mental Disorders

    (1994)
  • AndresenE.M. et al.

    Retest reliability of surveillance questions on health related quality of life

    J. Epidemiol. Community Health

    (2003)
  • BombardierC.H. et al.

    Posttraumatic stress disorder symptoms during the first six months after traumatic brain injury

    J. Neuropsychiatry Clin. Neurosciences

    (2006)
  • CallahanC.M. et al.

    Effectiveness of collaborative care for older adults with Alzheimer disease in primary care — a randomized controlled trial

    JAMA

    (2006)
  • CameronI.M. et al.

    Psychometric comparison of PHQ-9 and HADS for measuring depression severity in primary care

    Br. J Gen. Pract.

    (2008)
  • Centers for Disease Control and Prevention

    Behavioral Risk Factor Surveillance System User's Guide. U.S. Department of Health and Human Services

    (2005)
  • CorsonK. et al.

    Screening for depression and suicidality in a VA primary care setting: 2 items are better than 1 item

    Am. J. Managed Care

    (2004)
  • Diez-QuevedoC. et al.

    Validation and utility of the patient health questionnaire in diagnosing mental disorders in 1003 general hospital Spanish inpatients

    Psychosom. Med

    (2001)
  • FannJ.R. et al.

    Validity of the Patient Health Questionnaire-9 in assessing depression following traumatic brain injury

    J. Head Trauma Rehab.

    (2005)
  • FirstM.B. et al.

    Structured Clinical Interview for DSM-IV Axis I Disorders (SCID)

    (1996)
  • FleishmanJ.A. et al.

    Global self-rated mental health: associations with other mental health measures and with role functioning

    Med. Care

    (2007)
  • GilbodyS. et al.

    Diagnosing depression in primary care using self-completed instruments: UK validation of PHQ-9 and CORE-OM

    Br. J Gen. Pract.

    (2007)
  • GilbodyS. et al.

    Screening for depression in medical settings with the Patient Health Questionnaire (PHQ): a diagnostic meta-analysis

    J. Gen. Intern. Med.

    (2007)
  • GlasgowR.E. et al.

    A practical randomized trial to improve diabetes care

    J. Gen. Intern. Med.

    (2004)
  • HawthorneG. et al.

    The excess cost of depression in South Australia: a population-based study

    Aust. N. Zealand J. Psychiatry

    (2003)
  • HelzerJ.E. et al.

    The feasibility and need for dimensional psychiatric diagnoses

    Psychol. Med.

    (2006)
  • HoltzmanD.

    The Behavioral Risk Factor Surveillance System

  • HuangF.Y. et al.

    Using the Patient Health Questionnaire-9 to measure depression among racially and ethnically diverse primary care patients

    J. Gen. Intern. Med.

    (2006)
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