PHQ-9 vs GAD-7 : Arbre décisionnel clinique

Guide fondé sur des données probantes pour choisir entre les outils de dépistage de la dépression et de l'anxiété dans les milieux de soins primaires et de santé mentale. Quand utiliser l'un ou l'autre, et quand utiliser les deux.

Lecture de 12 min
Mis à jour en février 2026

Arbre de décision rapide

1
What is the primary presenting concern?

Depressed mood, anhedonia, hopelessness
Use: PHQ-9

Core depressive symptoms indicate depression-focused screening

Worry, nervousness, tension, panic
Use: GAD-7

Core anxiety symptoms indicate anxiety-focused screening

Both depression and anxiety symptoms
Use: Both

Comorbidity common - administer both for detailed assessment

Unclear or nonspecific distress
Use: Both

Undifferentiated symptoms require dual screening for accurate diagnosis

2
Does the patient have a known diagnosis?

Diagnosed Major Depressive Disorder
Use: PHQ-9

Use PHQ-9 for treatment monitoring and outcome tracking

Diagnosed Generalized Anxiety Disorder
Use: GAD-7

Use GAD-7 for symptom severity and treatment response

Both depression and anxiety diagnoses
Use: Both

Track both conditions separately to assess individual treatment response

No full clinical evaluation yet
Use: Both

Screening phase - cast wide net to identify primary condition

PHQ-9 vs GAD-7 : comparaison détaillée

PHQ-9

Patient Health Questionnaire-9

Éléments :9
Durée :2-3 minutes
Plage de scores :0-27
Seuil :≥10 (moderate depression)
Sensibilité :88%
Spécificité :88%

Points forts

  • Directly maps to DSM-5-TR MDD criteria
  • Item 9 screens for suicidality
  • Widely validated in primary care
  • Free and public domain
  • Sensitive to treatment change

Limites

  • May miss anxiety disorders
  • Less specific in medically ill patients
  • Somatic symptoms can inflate scores

Idéal pour

  • Depression screening in primary care
  • Treatment monitoring for antidepressants
  • Suicide risk assessment (item 9)
  • Outcome measurement in therapy
Essayer le questionnaire PHQ-9

GAD-7

Generalized Anxiety Disorder-7

Éléments :7
Durée :2-3 minutes
Plage de scores :0-21
Seuil :≥10 (moderate anxiety)
Sensibilité :89%
Spécificité :82%

Points forts

  • Screens for multiple anxiety disorders
  • Good performance for GAD, panic, social anxiety
  • Brief and well-tolerated
  • Strong psychometric properties
  • Sensitive to treatment change

Limites

  • Less specific for individual anxiety disorders
  • May miss depression if used alone
  • Somatic anxiety can inflate scores

Idéal pour

  • Anxiety disorder screening
  • Treatment monitoring for anxiolytics
  • Panic disorder detection
  • Social anxiety identification
Essayer le questionnaire GAD-7

Scénarios cliniques : quand utiliser chacun

Primary Care Annual Wellness Visit

Use: Both PHQ-9 and GAD-7

Universal screening for both depression and anxiety is recommended in primary care. Administering both takes <5 minutes and identifies comorbid conditions. 60% of patients with depression also have anxiety.

Fréquence :Annually, or when symptoms change

Patient Presents with Depressed Mood

Use: PHQ-9 first, consider GAD-7

Start with PHQ-9 to quantify depression severity and screen for suicidality (item 9). If PHQ-9 ≥10, add GAD-7 to rule out comorbid anxiety, which predicts worse depression outcomes and may require integrated treatment.

Fréquence :Every 2-4 weeks during treatment

Patient Presents with Anxiety Symptoms

Use: GAD-7 first, consider PHQ-9

Start with GAD-7 to assess anxiety severity. If GAD-7 ≥10, add PHQ-9 because depression commonly coexists with anxiety disorders (50% comorbidity) and may be the primary driver of distress.

Fréquence :Every 2-4 weeks during treatment

Monitoring Antidepressant Response

Use: PHQ-9 primary, GAD-7 secondary

PHQ-9 is the primary outcome for depression treatment. SSRIs/SNRIs also treat anxiety, so monitor GAD-7 to capture full treatment benefit. Target: 50% reduction in PHQ-9 by 8 weeks.

Fréquence :Weeks 2, 4, 8, 12, then quarterly

Therapy for Comorbid Depression and Anxiety

Use: Both PHQ-9 and GAD-7 equally

Track both conditions separately to understand which symptoms respond to therapy. Some interventions (e.g., behavioral activation) may improve depression faster than anxiety, or vice versa. Adjust treatment based on differential response.

Fréquence :Every session (weekly or biweekly)

Emergency Department Psychiatric Evaluation

Use: PHQ-9 for suicide screening

PHQ-9 item 9 screens for suicidal ideation. Positive screen (≥1 on item 9) requires detailed suicide risk assessment (C-SSRS). GAD-7 less critical in acute setting unless panic/anxiety is primary presentation.

Fréquence :Every ED visit with psychiatric component

Interprétation des présentations comorbides

High scores on both (PHQ-9 ≥10 AND GAD-7 ≥10)
Interprétation :Likely comorbid depression and anxiety
Action clinique :

Integrated treatment targeting both conditions. Consider SSRI/SNRI (treats both) + CBT. Higher risk of treatment resistance and worse functional impairment.

PHQ-9 much higher than GAD-7 (PHQ-9 ≥15, GAD-7 <10)
Interprétation :Primary depression with minimal anxiety
Action clinique :

Depression-focused treatment. Antidepressant monotherapy or behavioral activation. Monitor for emergent anxiety with treatment.

GAD-7 much higher than PHQ-9 (GAD-7 ≥15, PHQ-9 <10)
Interprétation :Primary anxiety disorder with minimal depression
Action clinique :

Anxiety-focused treatment. SSRI/SNRI or CBT with exposure therapy. Monitor for depression development if anxiety is chronic.

PHQ-9 item 9 positive (suicidal ideation), regardless of GAD-7
Interprétation :Elevated suicide risk requiring immediate assessment
Action clinique :

Full C-SSRS assessment, safety planning, crisis intervention. Address depression as primary target. Anxiety increases suicide risk.