PHQ-9: a plain-language definition

Definition

What phq-9 means

The PHQ-9 is a brief, validated questionnaire that measures depression symptoms. It asks nine questions about the past two weeks, mapped to the criteria for a major depressive episode: low mood, loss of interest, sleep and appetite changes, fatigue, guilt or worthlessness, trouble concentrating, slowed or restless movement, and thoughts of death or self-harm. Each item scores zero to three, for a total of zero to twenty-seven, sorted into minimal, mild, moderate, moderately severe, and severe bands.

In practice the PHQ-9 serves as both a screen and a tracker. At a first visit it gauges how heavy the depression is. Repeated over time, it shows whether treatment is moving the number, giving a clear record that memory cannot match. A drop from eighteen to seven across several weeks is concrete evidence of response. The ninth item, which asks about thoughts of death or self-harm, also flags safety concerns that the clinician follows up on directly.

This matters because the PHQ-9 anchors measurement-based care. shrinkMD repeats it alongside the GAD-7 at intervals so decisions about dose, medication, or adding therapy follow data rather than a vague sense of progress. If the score has not improved after an adequate trial, that is the signal to change the plan rather than wait.

A common misconception is that the PHQ-9 diagnoses depression. It does not; it measures severity and tracks change, while diagnosis is the clinician's work from the full picture. Another misread is that a single high score is the whole story. The number opens a conversation, and the clinician interprets it in context, including a careful response to any endorsement of the safety item.