The PHQ-9 is the 9-item depression module of the Patient Health Questionnaire (PHQ), a self-administered version of the PRIME-MD diagnostic interview for common mental disorders.

Evidence and context

Originally derived and validated in more than 6,000 adult primary care and obstetrics-gynaecology patients across two large studies.

In the main validation cohort, a PHQ-9 total score ≥10 had sensitivity and specificity of about 88% for DSM-IV major depression when compared with independent mental health professional interviews.

Higher PHQ-9 scores were strongly associated with functional impairment, disability days and health-care use, supporting its role as a measure of depression severity and treatment response.

Severity bands

PHQ-9 score	Severity band
0–4	Minimal or none
5–9	Mild
10–14	Moderate
15–19	Moderately severe
20–27	Severe

Use mainly with adults in primary care, mental health and general medical settings to screen for depressive symptoms, rate severity and monitor change over time. It should not be used as the sole basis for diagnosis or treatment decisions, and interpretation may be more complex in adolescents, older adults, and people with significant physical comorbidity or cognitive impairment.

This tool does not replace a clinical assessment for depression or suicide risk. Seek urgent review if there are concerns about safety, self-harm or rapidly worsening symptoms.

PHQ-9 (Patient Health Questionnaire-9) for Depression Severity