Research Summary

Diagnostic Accuracy of PHQ-9 and GAD-7 for Depression and Anxiety Screening in General Practice

Edited by:
Ashton L. Stahl

Key Highlights

  • PHQ-9 demonstrated 89.5% sensitivity and 91.2% negative predictive value for detecting depression.
  • GAD-7 showed 84.3% sensitivity and 90.8% negative predictive value for detecting anxiety disorders.
  • The area under the curve was 0.87 for PHQ-9 and 0.85 for GAD-7, indicating good diagnostic performance.
  • Both tools were evaluated against structured DSM-5–based clinical interviews as the reference standard.

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Early identification of depression and anxiety disorders in primary care remains a clinical priority. In a diagnostic accuracy study published in Journal of Heart Valve Disease, Amin and colleagues evaluated the performance of the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder-7 (GAD-7) in a general practice setting. The findings indicate that both screening tools demonstrate strong sensitivity and negative predictive value when compared with structured clinical interviews based on DSM-5 criteria.

The researchers conducted the study over 12 months in a general outpatient clinic and included 300 adults aged 18 to 65 presenting with non-emergency complaints. Patients with known psychiatric illness, those receiving psychiatric medication, and individuals with cognitive impairment were excluded. Participants completed self-administered PHQ-9 and GAD-7 questionnaires in the local language, using translation–back-translation validation methods.

All participants subsequently underwent a structured clinical interview conducted by a trained clinical psychologist using DSM-5 diagnostic criteria. The psychologist was blinded to screening results. The researchers calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) using the clinical interview as the reference standard. They generated receiver operating characteristic curves, and they determined area under the curve (AUC) values using SPSS version 25.

Study Findings

The mean age of participants was 38.2 ± 11.6 years; 60% were women, and 40% were men. Based on DSM-5–based structured interviews, 38% of participants were diagnosed with depression and 32% with anxiety disorders.

For depression screening, PHQ-9 identified 130 positive cases, of which 102 were confirmed by clinical diagnosis, with 28 false positives. The tool demonstrated a sensitivity of 89.5%, a specificity of 78.2%, a PPV of 74.2%, and an NPV of 91.2%. The AUC for PHQ-9 was 0.87.

For anxiety screening, GAD-7 identified 115 positive cases, with 86 confirmed diagnoses and 29 false positives. Sensitivity was 84.3%, specificity 81.7%, PPV 70.4%, and NPV 90.8%. The AUC for GAD-7 was 0.85. ROC analysis indicated good overall diagnostic performance for both tools, with PHQ-9 showing slightly higher overall accuracy.

Clinical Implications

According to the study authors, the high sensitivity and negative predictive values of PHQ-9 and GAD-7 make them particularly suitable for screening purposes in general practice. The authors noted that high NPV is especially important in primary care settings, where clinicians aim to rule out conditions and avoid unnecessary interventions or referrals reliably. They also emphasized that both instruments are self-administered, time-efficient, and feasible in busy outpatient settings.

Expert Commentary

“In summary, our study contributes to the growing body of evidence supporting the use of PHQ-9 and GAD-7 for early detection of depression and anxiety in general practice. Their high diagnostic accuracy, ease of use, and feasibility make them suitable for routine implementation. However, clinicians should remain aware of contextual factors such as literacy, cultural differences, and coexisting medical conditions when interpreting results,” the researchers concluded.

References

Amin SA, Prajapati JP, Dhanani VS. Assessment of mental health screening tools in general practice for early detection of depression and anxiety disorders: a diagnostic accuracy study. Journal of Heart Valve Disease. 2025;30(7):213-217. https://www.icr-heart.com/article/assessment-of-mental-health-screening-tools-in-general-practice-for-early-detection-of-depression-and-anxiety-disorders-a-diagnostic-accuracy-study-2474/. Accessed March 3, 2026.