If you're tracking client progress over time, PHQ-9 and GAD-7 are two of the most widely used, validated outcome measures in mental health practice — but they measure different things, and practitioners new to structured outcome tracking sometimes reach for the wrong one, or don't realise they can (and often should) use both.
Here's a direct comparison, and how to decide which one fits a given client.
Quick comparison
| PHQ-9 | GAD-7 | |
|---|---|---|
| Full name | Patient Health Questionnaire-9 | Generalized Anxiety Disorder-7 |
| Measures | Depression symptom severity | Anxiety symptom severity |
| Number of items | 9 | 7 |
| Score range | 0–27 | 0–21 |
| Typical severity bands | 0–4 minimal, 5–9 mild, 10–14 moderate, 15–19 moderately severe, 20–27 severe | 0–4 minimal, 5–9 mild, 10–14 moderate, 15–21 severe |
| Best used for | Screening and monitoring depressive symptoms over time | Screening and monitoring anxiety symptoms over time |
| Typical time to administer | 2–3 minutes | 2–3 minutes |
When to use PHQ-9
PHQ-9 is built around the DSM criteria for major depressive disorder, asking clients to rate how often they've experienced 9 specific symptoms (low mood, sleep disturbance, appetite changes, concentration difficulty, and others) over the past two weeks. It's a strong fit as a standard intake screener and as a repeated measure to track whether depressive symptoms are trending up or down across a course of treatment.
When to use GAD-7
GAD-7 focuses specifically on generalized anxiety symptoms — excessive worry, restlessness, difficulty relaxing — over the same two-week window. It's shorter than PHQ-9 and was designed as a fast, repeatable screen rather than a full diagnostic tool.
Why not just pick one?
Depression and anxiety symptoms overlap and frequently co-occur. A client screening high on PHQ-9 but not GAD-7 (or the reverse) tells you something clinically useful about where to focus — and a client tracked on only one measure can have a real shift in the other symptom cluster go unnoticed. Many practitioners administer both at intake and at regular intervals afterward, rather than choosing one over the other.
Using outcome measures alongside session notes
Whichever measure — or combination — fits your caseload, the value comes from tracking scores consistently over time, not from a single point-in-time snapshot. Recording scores as part of your structured session notes (rather than in a separate spreadsheet you have to remember to update) makes the trend visible at a glance during a review, and keeps it in the same audit trail as the rest of the client's record.
For more on what needs to be in that record in the first place, see our HPCSA record-keeping guide.
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