The PHQ-9 Depression Screening Tool: A Complete Clinician Guide

The Patient Health Questionnaire-9 (PHQ-9) is the most widely used depression screening instrument in the world. Brief, free, and closely aligned with diagnostic criteria, it is a mainstay of primary care, mental health clinics, and integrated care settings. This guide covers what the PHQ-9 measures, how it is scored, how to interpret the severity bands, and how to handle the critical suicide-risk item.

What the PHQ-9 measures

The PHQ-9 assesses the severity of depressive symptoms over the past two weeks. Its nine items map directly onto the nine diagnostic criteria for a major depressive episode, covering low mood, loss of interest, sleep and appetite changes, fatigue, concentration difficulties, feelings of worthlessness or guilt, psychomotor changes, and thoughts of death or self-harm. This close alignment with diagnostic criteria makes the PHQ-9 useful both as a screener and as a way to gauge symptom count and severity.

The nine items and response scale

For each item, respondents indicate how often they have been bothered by the symptom over the last two weeks, on a four-point scale:

• 0 - Not at all
• 1 - Several days
• 2 - More than half the days
• 3 - Nearly every day

A tenth question (not scored in the total) asks how much any symptoms have interfered with functioning, which adds valuable context.

How to score the PHQ-9

Summing the nine items gives a total from 0 to 27. The calculation is simple, but manual scoring across many patients each day still invites errors, which is one reason clinics increasingly use automated scoring to guarantee accuracy and consistency.

PHQ-9 severity bands and cut-off

The total maps onto these commonly used severity ranges:

• 1-4: Minimal depression
• 5-9: Mild depression
• 10-14: Moderate depression
• 15-19: Moderately severe depression
• 20-27: Severe depression

A score of 10 or above is the most commonly cited cut-off for probable major depression and typically prompts further clinical evaluation. As always, the PHQ-9 supports but does not replace qualified clinical judgement - a positive screen calls for a full assessment before any diagnosis.

Item 9 and suicide risk

The ninth item asks about thoughts of being better off dead or of self-harm. Any positive response - even a "several days" rating - should trigger a direct suicide risk assessment, regardless of the overall total. A low total score does not rule out risk. Clinicians should have a clear protocol for responding to a positive item 9, and digital platforms can be configured to flag it prominently in the report so it is never overlooked.

The PHQ-2 pre-screen

The first two PHQ-9 items form the PHQ-2, a two-question pre-screen covering low mood and loss of interest. Scored 0-6, a PHQ-2 result at or above the usual threshold indicates that the full PHQ-9 should be administered. This stepped approach is efficient in high-volume settings such as primary care depression screening, where a quick first pass conserves time.

PHQ-9 compared with the BDI-II

Clinicians often weigh the PHQ-9 against the BDI-II. Both measure depression severity, but the PHQ-9 is shorter (9 items versus 21), free to use, and mapped directly to diagnostic criteria, making it ideal for rapid screening and monitoring. The BDI-II offers more granular symptom coverage and is often favoured in specialist mental health settings. Many practices use the PHQ-9 for screening and reserve the BDI-II for detailed assessment. For anxiety, the PHQ-9 pairs naturally with the GAD-7.

Using the PHQ-9 digitally

Digital administration lets patients complete the PHQ-9 on any device before or during a visit, calculates the total and severity band instantly, and produces a clinician-grade PDF report. Repeat administrations plot neatly over time, supporting measurement-based care, and item 9 can be auto-flagged for immediate attention - all while reducing paperwork in busy clinics.

Key takeaways

• The PHQ-9 is a 9-item depression screener mapped to major depressive episode criteria, scored 0-27.
• Severity bands: 1-4 minimal, 5-9 mild, 10-14 moderate, 15-19 moderately severe, 20-27 severe.
• A score of 10 or above is the usual cut-off for probable major depression.
• Any positive response to item 9 requires a direct suicide risk assessment, whatever the total.
• The PHQ-2 acts as a fast two-item pre-screen; digital scoring adds speed, accuracy, and risk flagging.