Brief Patient Health Questionnaire (Brief PHQ)

1. Abstract

The Brief Patient Health Questionnaire (Brief PHQ) represents an abbreviated, highly efficient diagnostic self-report instrument derived from the full Patient Health Questionnaire (PHQ) and the Primary Care Evaluation of Mental Disorders (PRIME-MD) diagnostic system. Designed specifically for primary care and general medical environments, the Brief PHQ streamlines the systematic evaluation of the most prevalent psychiatric disorders encountered in ambulatory medicine, with primary emphasis on major depressive disorder and panic disorder, while concurrently screening for psychosocial stressors, functional impairment, physical/sexual trauma, psychotropic medication utilization, and female reproductive-cycle-related mood disturbances. The instrument integrates the full 9-item depression module (PHQ-9), a 5-item panic syndrome algorithm, a standardized single-item functional impairment metric, a 10-item psychosocial stressor checklist, an interpersonal violence screen, and a targeted 6-item women’s health module.

Psychometrically, the Brief PHQ demonstrates robust diagnostic concordance with independent structured clinical interviews conducted by mental health professionals, exhibiting sensitivity values ranging from 0.73 to 0.88 and specificity values exceeding 0.88 to 0.94 for threshold depressive and anxiety syndromes. The depression component (PHQ-9) possesses high internal consistency (Cronbach’s alpha between 0.86 and 0.89) and solid test-retest reliability ($r = 0.84$). Construct validity is corroborated by strong gradients of association between composite distress scores and validated functional status markers, such as the Short Form Health Survey (SF-20 / SF-36), ambulatory healthcare utilization, and workplace disability. Overall, the Brief PHQ operationalizes DSM-IV and subsequent DSM-5 diagnostic criteria into a self-administered, clinically actionable format that dramatically reduces clinician burden while facilitating early detection, clinical decision-making, and measurement-based care across diverse medical populations.

2. Keywords

Brief Patient Health Questionnaire, Brief PHQ, PHQ-9, PRIME-MD, depression screening, panic disorder, primary care psychometrics, psychosocial stressors, diagnostic validity, functional impairment

3. Authors

The Brief Patient Health Questionnaire was developed by a team of prominent psychiatric and medical researchers led by:

• Robert L. Spitzer, M.D. — Professor of Psychiatry, Department of Psychiatry, Columbia University College of Physicians and Surgeons; former Chief of the Department of New Research Training at the New York State Psychiatric Institute; Chair of the American Psychiatric Association Task Force on DSM-III. Contact (historical): Columbia University, New York, NY.
• Janet B. W. Williams, D.S.W. — Professor of Clinical Psychiatric Social Work (in Psychiatry), Columbia University College of Physicians and Surgeons; Research Scientist, New York State Psychiatric Institute, New York, NY.
• Kurt Kroenke, M.D., MACP — Professor of Medicine, Indiana University School of Medicine; Senior Research Scientist, Regenstrief Institute, Inc.; Research Scientist, Center for Health Services and Implementation Research, Roudebush VA Medical Center, Indianapolis, IN.
• Collaborating Investigators — With contributions from Mark Linzer, M.D., Frank deGruy III, M.D., Steven R. Hahn, M.D., David Brody, M.D., and colleagues across the PRIME-MD 1000 and PHQ Primary Care validation networks.

The instrument was developed with funding through an educational grant from Pfizer Inc. The proprietary identifiers PRIME-MD® and PRIME-MD TODAY® are registered trademarks of Pfizer Inc., but the questionnaire was placed in the public domain by the authors to facilitate open clinical adoption and academic inquiry.

4. Purpose

Mental health conditions, particularly depressive and anxiety disorders, represent primary contributors to the global burden of disease and rank among the most common presenting complaints in primary care medicine. However, epidemiological and health services investigations throughout the late 20th century consistently demonstrated that primary care physicians unrecognized or misdiagnosed between 30% and 50% of psychological morbidity in routine outpatient consultations. The primary obstacles included severe time constraints, patient hesitation to present emotional symptoms, physician uncertainty regarding formal psychiatric criteria, and the burdensome, complex nature of traditional clinician-administered diagnostic schedules.

To overcome these barriers, Spitzer and colleagues originally constructed the Primary Care Evaluation of Mental Disorders (PRIME-MD), which combined a one-page patient questionnaire with a structured clinician-administered interview booklet. While PRIME-MD substantially improved detection rates, its requirement for direct clinician administration of extensive diagnostic modules limited widespread implementation within high-volume primary care practices. In response, the authors developed the fully patient-administered Patient Health Questionnaire (PHQ), and subsequently synthesized its highest-yield components into the Brief Patient Health Questionnaire (Brief PHQ).

The clinical and psychometric purpose of the Brief PHQ encompasses several complementary objectives:

• Case Identification and Categorical Diagnosis: The Brief PHQ provides criterion-referenced algorithms aligned with the Diagnostic and Statistical Manual of Mental Disorders (DSM) for major depressive disorder, other depressive syndromes (dysthymia / persistent depressive disorder, minor depressive disorder), and panic disorder. It allows clinicians to rapidly distinguish between subthreshold distress and definitive diagnostic pathology without requiring extensive psychiatric interviews.
• Symptom Severity Quantification: By employing the validated PHQ-9 scale as its depression axis, the tool enables continuous severity scoring (ranging from 0 to 27) that correlates linearly with functional impairment, biological indicators of stress, and clinical prognosis. This dual categorical-dimensional capability is foundational for modern measurement-based care (MBC), allowing practitioners to titrate pharmacotherapy or psychotherapy based on objective numeric thresholds.
• Comprehensive Biopsychosocial Triage: Medical comorbidities frequently interact with life events, intimate partner conflict, socio-economic strain, and gender-specific endocrine transitions. The Brief PHQ systematically surveys ten discrete psychosocial stressor domains, past physical or sexual victimization, and current psychotropic medication regimens, offering clinicians a holistic overview of the patient’s biopsychosocial context within a 3- to 5-minute self-administered assessment.
• Specialized Screening for Women’s Health: A distinct module screens for reproductive-related affective vulnerability, including premenstrual dysphoric disorder (PMDD) symptoms, perimenopausal irregularities, postpartum depression, emotional sequlae of miscarriage, and infertility-related distress, optimizing care within obstetrics and gynecology practices.

5. Psychological Construct

The Brief PHQ measures a multidimensional constellation of psychological, affective, somatic, and behavioral constructs. Rather than assessing a single undifferentiated construct of “neuroticism” or “general distress,” the instrument isolates several correlated yet distinct psychiatric and psychosocial dimensions:

Major Depressive Syndrome and Anhedonia

The primary affective construct measured by the Brief PHQ corresponds directly to the diagnostic construct of Major Depressive Episode as operationalized in DSM-IV and DSM-5. This construct is structured around two core pathognomonic cardinal features:

• Depressed Mood: Persistent feelings of sadness, dysphoria, emptiness, tearfulness, or hopelessness.
• Anhedonia: Pervasive loss of interest, pleasure, or engagement in previously rewarding physical, intellectual, or interpersonal activities.

In addition to these cardinal affective markers, the construct comprises seven somatic and cognitive criterion domains: neurovegetative sleep disturbances (insomnia or hypersomnia), psychomotor alterations (objective retardation or subjective agitation), chronic asthenia (energy depletion and excessive fatigue), appetite and metabolic shifts (anorexia or compensatory hyperphagia), cognitive dysfunctions (impaired executive concentration, decision-making indecisiveness), self-directed negative appraisals (feelings of guilt, personal worthlessness, perceptions of failure), and cognitive distortions regarding mortality (passive death wishes, active suicidal ideation, or non-suicidal self-directed violence).

Panic Disorder and Paroxysmal Autonomic Arousal

The anxiety construct assessed within the Brief PHQ reflects panic disorder characterized by acute, paroxysmal surges of catastrophic fear that occur spontaneously (“out of the blue”) without an obvious contextual trigger. This construct encompasses both the subjective psychological experience of impending doom or dread and profound autonomic hyperactivity, including cardiorespiratory symptoms (dyspnea, palpitations, tachycardia), vestibular disturbances (lightheadedness, presyncope), neurological signs (paresthesias, peripheral numbness), and gastrointestinal distress (nausea, visceral discomfort). The construct further captures anticipatory anxiety, specifically persistent worry regarding the recurrence or physical consequences of subsequent attacks.

Functional Impairment and Disability

Grounded in the World Health Organization’s conceptualization of functioning and disability, the Brief PHQ evaluates the clinical significance of identified symptoms through a dedicated global functional impairment item. This construct captures the extent to which psychological disturbances disrupt three fundamental behavioral domains: occupational or academic performance, domestic and home management, and interpersonal social relationships.

Psychosocial Environmental Stressors

The psychosocial stressor construct reflects chronic ambient stress and discrete negative life events distributed across multiple domains: somatic health anxieties, body image and physical appearance distress, sexual dissatisfaction or hypoactive sexual desire, romantic and martial friction, caregiving strain (pediatric or eldercare burden), workplace and educational pressures, financial instability, social isolation (absence of a reliable social support network), recent acute adverse life events, and intrusive traumatic memories or nightmares characteristic of post-traumatic stress.

Interpersonal Trauma and Victimization

The interpersonal trauma construct measures past-year exposure to domestic abuse, physical assault (being hit, slapped, or kicked), and non-consensual sexual coercion. This construct serves as a high-yield screener for ongoing interpersonal violence, which correlates strongly with treatment-resistant affective disorders and somatic symptom amplification.

Female Reproductive-Associated Affective Instability

This gender-specific construct isolates mood lability and psychological symptoms temporally linked to reproductive biological states, particularly premenstrual luteal-phase dysphoria, post-partum vulnerability, perinatal bereavement, and psychological distress associated with infertility.

6. Theoretical Framework

The Brief PHQ is grounded in the convergence of two major paradigms in behavioral science and clinical medicine: the Criteria-Oriented Neo-Kraepelinian Diagnostic Framework and the Biopsychosocial Model of Medicine.

The Neo-Kraepelinian Diagnostic Model and the DSM Revolution

During the late 20th century, psychiatric nosology underwent a fundamental paradigm shift away from psychoanalytic formulations toward descriptive, operationalized, criteria-based diagnostic systems, championed by Robert L. Spitzer during the development of DSM-III and DSM-IV. The fundamental theoretical premise of this framework is that mental disorders represent distinct clinical syndromes characterized by specific clusters of observable signs, cognitive distortions, and self-reported subjective experiences that exhibit predictable natural histories, biological correlates, and therapeutic responses.

Under this theoretical assumption, diagnostic validity is maximized when clinical assessment tools operationalize diagnostic criteria into standardized, unambiguous questions. The Brief PHQ directly translates DSM diagnostic algorithms into self-report format without altering clinical thresholds. Rather than treating depression or panic solely as continuous, indistinct latent traits, the instrument maintains dual psychometric utility: it preserves categorical diagnostic fidelity (evaluating whether a patient meets the requisite symptom count and duration criteria for a clinical disorder) while enabling continuous measurement of underlying symptom severity.

The Biopsychosocial Model and Primary Care Epidemiology

Complementing its categorical diagnostic foundation, the Brief PHQ is theoretically anchored in George Engel’s Biopsychosocial Model. Engel postulated that disease outcomes and patient suffering cannot be understood strictly through isolated biological or pathophysiological mechanisms; rather, they arise from complex interactions between biological vulnerabilities, psychological states, and interpersonal or socio-environmental forces.

In medical outpatients, somatic symptoms (fatigue, sleep disturbance, gastrointestinal pain) frequently represent the primary physical manifestations of unaddressed emotional disorders. By juxtaposing categorical syndromal modules (PHQ-9 and panic screens) alongside detailed psychosocial stressor indices, interpersonal trauma screening, and reproductive endocrinological milestones, the Brief PHQ operationalizes the biopsychosocial model for rapid clinical practice. It conceptualizes the medical encounter as a holistic evaluation wherein psychological distress, life stress, and somatic pathology continuously modulate one another.

7. Validity

The psychometric validity of the Brief PHQ and its constituent modules has been established across extensive multisite validation trials involving thousands of primary care and specialty clinic patients.

Criterion and Diagnostic Concordance Validity

In the seminal validation studies led by Spitzer, Kroenke, Williams, and colleagues (including the PRIME-MD 1000 and the 3,000-patient Primary Care PHQ study published in JAMA, 1999), self-administered responses were systematically compared against blinded, independent clinical diagnostic interviews conducted by mental health professionals (clinical psychologists and board-certified psychiatrists) using structured diagnostic schedules. Key diagnostic validity metrics include:

• Depression Module (PHQ-9): When evaluated using the categorical diagnostic algorithm (requiring 5 or more of the 9 symptoms present at least “more than half the days,” with at least one symptom being depressed mood or anhedonia), the sensitivity for identifying Major Depressive Disorder was 0.88, with an outstanding specificity of 0.88. Using a dimensional threshold score of $ge 10$, sensitivity was 0.88 and specificity was 0.88; a cutpoint of $ge 15$ yielded a specificity of 0.96 for major depressive episodes.
• Panic Disorder Module: For the panic algorithm (requiring positive responses across panic attacks, recurrent nature, spontaneous presentation, associated worry, and at least 4 prominent autonomic symptoms), the Brief PHQ exhibited a sensitivity of 0.73 to 0.81 and a high specificity of 0.94 to 0.99, demonstrating that false-positive diagnoses of panic disorder are rare when the full algorithmic criteria are satisfied.

Construct, Convergent, and Discriminant Validity

Construct validity was evaluated by assessing the relationship between Brief PHQ diagnoses and functional health status measured by the MOS 20-Item and 36-Item Short-Form Health Surveys (SF-20 / SF-36). Patients diagnosed with major depressive syndrome or panic disorder on the Brief PHQ demonstrated profound, statistically significant decrements ($p < .001$) across all health-related quality of life subscales, including physical functioning, role functioning, social functioning, mental health, and bodily pain.

A monotonic, stepwise gradient was observed: patients with subthreshold or minor depressive syndromes exhibited intermediate functional impairments, whereas those meeting full major depression criteria demonstrated disability scores comparable to or exceeding those observed in severe chronic medical illnesses such as congestive heart failure, end-stage renal disease, and chronic obstructive pulmonary disease. Furthermore, the Brief PHQ psychosocial stressor count showed strong convergent correlations ($r = 0.45$ to $0.58$) with global perceived stress measures and healthcare utilization metrics, including primary care visits, emergency department contacts, and prescription drug counts.

Predictive and Longitudinal Validity

Longitudinal evaluation demonstrates that Brief PHQ baseline scores robustly predict healthcare outcomes over 12- to 24-month follow-up windows. Elevated baseline PHQ-9 scores independently predict persistent work absenteeism, short-term disability claims, increased somatic symptom chronicity, and elevated cardiovascular morbidity. Clinically, a reduction of $ge 5$ points on the continuous PHQ-9 subscale over the course of treatment corresponds closely to clinician-rated Global Clinical Impression (CGI) improvements and significant restoration of employment functioning.

8. Reliability

The Brief PHQ demonstrates excellent empirical reliability across diverse patient cohorts, clinical settings, and socio-demographic backgrounds.

Internal Consistency Reliability

The internal consistency of the depression module (PHQ-9) embedded within the Brief PHQ has been confirmed across diverse medical cohorts. In the original primary care derivation sample ($N = 3,000$), Cronbach’s alpha for the 9 depression items was 0.89. Subsequent validation in specialized medical cohorts, including 344 patients enrolled in the English-language Diabetes Self-Management Study, demonstrated an alpha coefficient of 0.88 (observed mean score = 6.40, standard deviation = 5.73, range 0–23). In obstetrics-gynecology settings, alpha coefficients typically range between 0.86 and 0.89, indicating high inter-item covariance and construct homogeneity without excessive item redundancy.

Test-Retest Reliability

Because the Brief PHQ assesses affective and anxiety states that are subject to dynamic clinical fluctuations, test-retest reliability has been assessed over short intervals (typically 48 hours to 2 weeks). In structured retest paradigms where patients completed the instrument in clinic and again via telephone or follow-up questionnaire within 48 to 72 hours, the test-retest correlation coefficient for the PHQ-9 continuous score was $r = 0.84$.

Diagnostic agreement across categorical classifications demonstrated high stability, with Cohen’s kappa coefficients ($kappa$) ranging from 0.65 to 0.78 for depressive syndromes and 0.68 for the panic disorder module. These metrics indicate reliable test stability, confirming that the Brief PHQ captures consistent clinical features rather than transient momentary noise.

Inter-Rater and Inter-Format Equivalence

Studies evaluating the measurement equivalence between self-administered paper-and-pencil Brief PHQ administrations, clinician-guided administrations, computerized electronic surveys, and interactive voice response (IVR) systems have revealed near-identical score distributions (intraclass correlation coefficients > 0.90), demonstrating that the self-report modality does not compromise diagnostic stability relative to interview formats.

9. Factor Analysis

Extensive exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) have delineated the structural architecture of the Brief PHQ.

Factor Structure of the Depression Component (PHQ-9)

Across numerous factor-analytic studies, the PHQ-9 component has been evaluated to determine whether it functions as a strictly unidimensional scale or reflects distinct sub-facets of depressive symptomatology:

• Unidimensional Model: In initial primary care validation cohorts, a dominant single-factor solution accounted for the majority of common variance (often exceeding 45% to 54%). All 9 items consistently demonstrate moderate to strong primary factor loadings ranging from 0.52 to 0.79. The highest loadings are consistently observed for Item 1 (Anhedonia: $\lambda \approx 0.74$), Item 2 (Depressed Mood: $\lambda \approx 0.78$), and Item 6 (Worthlessness/Failure: $\lambda \approx 0.71$).
• Bifactor and Two-Factor Models: In larger, more heterogeneous medical and psychiatric populations, CFA analyses typically support a superior fit for a two-factor correlated model or a bifactor structure separating Somatic/Vegetative Symptoms (Item 3: Sleep, Item 4: Fatigue, Item 5: Appetite, Item 8: Psychomotor) from Cognitive/Affective Symptoms (Item 1: Anhedonia, Item 2: Depressed Mood, Item 6: Guilt/Failure, Item 7: Concentration, Item 9: Suicidal Ideation). CFA fit indices for this two-factor model routinely yield excellent parameters: Comparative Fit Index ($CFI > 0.96$), Tucker-Lewis Index ($TLI > 0.95$), and Root Mean Square Error of Approximation ($RMSEA < 0.05$).

Structural Divergence: Panic vs. Depression Modules

When the panic disorder module and the PHQ-9 are entered simultaneously into multidimensional exploratory factor analyses, the panic items (sudden attacks, spontaneous attacks, physical panic symptoms) load onto a distinct factor ($lambda = 0.65 – 0.85$) that is psychometrically separate from the general depressive factor. This structural divergence supports the dual-module architecture of the Brief PHQ, demonstrating that while anxiety and depression frequently co-occur in primary care, they maintain discrete latent factor identities.

Psychosocial Stressor Dimension

Factor analyses of the 10-item psychosocial stressor checklist reveal a multidimensional structure organized across three main domains: Socio-Environmental Stressors (financial strain, work/school stress, social isolation), Interpersonal/Relational Stressors (partner difficulties, family caregiving strain), and Health/Physical Stressors (health worry, weight/appearance concerns, sexual dissatisfaction). These stress factors correlate moderately with the primary depression and panic factors ($r \approx 0.35 – 0.50$), illustrating that life stressors operate as related external triggers and maintaining factors rather than redundant manifestations of affective illness.

10. Instrument / Measurement Tool

The Brief Patient Health Questionnaire is formatted as a structured, self-administered clinical assessment instrument designed to be completed by patients in ambulatory waiting rooms, examination areas, or via electronic patient portals prior to clinical encounters.

Structural Architecture

• Test Type: Clinical screening and diagnostic self-report instrument.
• Administration Format: Paper-and-pencil questionnaire, digital patient portal, tablet, or web application.
• Target Population: Adult primary care, outpatient specialty, and general medical patients (aged 18 and older).
• Completion Time: Approximately 3 to 5 minutes.
• Primary Modules:
  • Module 1: Depression (PHQ-9) — 9 DSM criteria items rated on a 4-point temporal frequency scale.
  • Module 2: Anxiety / Panic — 5 items utilizing conditional branching (skip-pattern) and Yes/No dichotomous responses.
  • Module 3: Global Functional Impairment — 1 item evaluating difficulties across work, home, and interpersonal domains.
  • Module 4: Psychosocial Stressors — 10 items evaluated across a 3-point severity scale.
  • Module 5: Interpersonal Trauma — 1 past-year physical/sexual abuse screening item (Yes/No).
  • Module 6: Open-Ended Stressor Query — Free-text qualitative entry for the patient’s most stressful life event.
  • Module 7: Psychotropic Medication — 1 item screening for current medication for anxiety, depression, or stress (Yes/No).
  • Module 8: Women’s Health Module — 6 specialized reproductive and perimenstrual health items for female patients.

Response Formats

• Depression Module (PHQ-9): 4-point Likert frequency scale assessing symptoms over the past 2 weeks:
  • 0 = Not at all
  • 1 = Several days
  • 2 = More than half the days
  • 3 = Nearly every day
• Panic Disorder Module: Dichotomous format (NO / YES). Includes an explicit skip rule: If Item 2a (“In the last 4 weeks, have you had an anxiety attack…”) is answered “NO,” the respondent skips directly to Question 3.
• Functional Impairment: 4-point ordinal categorical scale: “Not difficult at all,” “Somewhat difficult,” “Very difficult,” “Extremely difficult.”
• Psychosocial Stressor Checklist: 3-point ordinal scale assessing impact over the past 4 weeks: “Not bothered,” “Bothered a little,” “Bothered a lot.”
• Trauma & Medication Items: Dichotomous format (NO / YES).
• Women’s Health Module: Multiple-choice categorical and dichotomous options (NO / YES / NO or does not apply).

Diagnostic Scoring Algorithms and Dimensional Thresholds

• Categorical Diagnostic Algorithm for Major Depressive Disorder (MDD): Requires at least 5 of the 9 depression items to be rated positive. An item is positive if scored $ge 2$ (“More than half the days”), except for Item 9 (suicidal ideation), which counts as positive if scored $ge 1$ (“Several days”). Critically, at least one of the positive symptoms must be Item 1a (Little interest or pleasure) or Item 1b (Feeling down, depressed, or hopeless).
• Categorical Algorithm for Other Depressive Syndrome: Requires 2, 3, or 4 depressive symptoms scored positive ($ge 2$; Item 9 positive if $ge 1$), with at least one cardinal symptom (Item 1a or 1b).
• Dimensional Severity Scoring (PHQ-9): Calculated by summing all 9 depression items (range: 0 to 27):
  • 0 – 4: Minimal or no depression
  • 5 – 9: Mild depression
  • 10 – 14: Moderate depression (recommended clinical threshold for active treatment consideration)
  • 15 – 19: Moderately severe depression
  • 20 – 27: Severe major depression

  Handling of Ambiguous / Missing Data: If two consecutive numbers are circled, score the higher (more distressed) number. If numbers are not consecutive, do not score the item. If more than 1 item is missing across the 9 items, set the composite scale value to missing.

• Panic Disorder Diagnostic Algorithm: A probable panic syndrome is identified if the patient endorses all four of the following criteria:
  1. Item 2a = YES (anxiety attack in the last 4 weeks)
  2. Item 2b = YES (has happened before)
  3. Item 2c = YES (attacks come suddenly out of the blue)
  4. Item 2d = YES (attacks bother a lot or worry about having another attack)
  5. Item 2e = Prominent physical symptoms (shortness of breath, sweating, heart racing, dizziness, tingling, or nausea).
• Psychosocial Stressor Scoring: Items marked “Bothered a lot” are flagged for targeted clinical exploration and social work or behavioral health referral.
• Trauma Screen (Question 5): Any “YES” indicates recent exposure to domestic or sexual violence, prompting immediate clinical safety evaluation.
• Item 1i (Suicide Risk Screen): Any score of 1, 2, or 3 requires immediate direct clinical assessment for suicidal ideation, intent, plan, and lethal access.

11. Permissions & Fee and Test Year

The Brief Patient Health Questionnaire was developed and copyrighted in 1999 by Drs. Robert L. Spitzer, Janet B. W. Williams, Kurt Kroenke, and colleagues, with support from an educational grant provided by Pfizer Inc.

Licensing and Fee Structure: The developers and copyright holders established an open-access distribution policy. As stated on the official instrument: “Developed by Drs. Robert L. Spitzer, Janet B.W. Williams, Kurt Kroenke and colleagues, with an educational grant from Pfizer Inc. No permission required to reproduce, translate, display or distribute.” Consequently, the Brief PHQ is completely free of charge and may be reproduced, translated, electronically adapted, and utilized in clinical practice, public health programs, and academic research without royalty fees or prior written licensing agreements, provided proper bibliographic citation is maintained. The trade names PRIME-MD® and PRIME-MD TODAY® remain registered trademarks of Pfizer Inc.

12. References

• Kroenke, K., Spitzer, R. L., & Williams, J. B. W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x
• Spitzer, R. L., Kroenke, K., Williams, J. B. W., & the Patient Health Questionnaire Primary Care Study Group. (1999). Validation and utility of a self-report version of PRIME-MD: The PHQ primary care study. JAMA, 282(18), 1737–1744. https://doi.org/10.1001/jama.282.18.1737
• Spitzer, R. L., Williams, J. B. W., Kroenke, K., Hornyak, R., & McMurray, J. (2000). Validity and utility of the PRIME-MD Patient Health Questionnaire in assessment of 3000 obstetric-gynecologic patients: The GYN-PHQ study. American Journal of Obstetrics and Gynecology, 183(3), 759–769. https://doi.org/10.1067/mob.2000.106580
• Kroenke, K., & Spitzer, R. L. (2002). The PHQ-9: A new depression diagnostic and severity measure. Psychiatric Annals, 32(9), 509–515. https://doi.org/10.3928/0048-5713-20020901-06
• Spitzer, R. L., Williams, J. B. W., Kroenke, K., Linzer, M., deGruy, F. V., Hahn, S. R., Brody, D., & Johnson, J. G. (1994). Utility of a new procedure for diagnosing mental disorders in primary care: The PRIME-MD 1000 study. JAMA, 272(22), 1749–1756. https://doi.org/10.1001/jama.1994.03520220043029
• Kroenke, K., Spitzer, R. L., Williams, J. B. W., & Löwe, B. (2010). The Patient Health Questionnaire Somatic, Anxiety, and Depressive Symptom Scales: A systematic review. General Hospital Psychiatry, 32(4), 345–359. https://doi.org/10.1016/j.genhosppsych.2010.03.006

13. Items of the Scale (Questionnaire)