The PHQ-9: A Therapist's Guide to Scoring, Interpreting, and Tracking Over Time

The Patient Health Questionnaire-9 is probably the most widely used depression screening instrument in the world. If you're a therapist, you've almost certainly encountered it. But there's a difference between using the PHQ-9 and using it well.

This guide covers what the PHQ-9 actually measures, how to score and interpret it, what the severity bands mean clinically, and how to use PHQ-9 data over time to make better treatment decisions.

What the PHQ-9 measures

The PHQ-9 is a nine-item self-report questionnaire based on the DSM diagnostic criteria for major depressive disorder. Each item asks about the frequency of a specific symptom over the past two weeks, scored from 0 ("not at all") to 3 ("nearly every day").

The nine items cover: loss of interest or pleasure, depressed mood, sleep disturbance, fatigue, appetite changes, feelings of failure or guilt, difficulty concentrating, psychomotor changes, and suicidal ideation.

Total scores range from 0 to 27.

A few things worth noting: the PHQ-9 is a screening and severity measure, not a diagnostic tool. A high score suggests depression, but a diagnosis still requires clinical judgment. It also measures symptom frequency, not intensity — a client could rate every item as "several days" (1) and still be in significant distress during those days.

How to score it

Scoring is straightforward: add up the responses for all nine items. The total falls into one of five severity bands.

0–4: Minimal or none. Scores in this range suggest no clinically significant depression. This is your baseline for clients who aren't presenting with depressive symptoms.

5–9: Mild. The client is endorsing some symptoms but not at a level that typically warrants treatment for depression specifically. Worth monitoring, especially if scores are trending upward.

10–14: Moderate. This is often the clinical decision point. Scores of 10 and above have strong sensitivity and specificity for major depressive disorder. For many therapists, this is where treatment planning shifts to explicitly address depressive symptoms.

15–19: Moderately severe. Active treatment is strongly indicated. Clients in this range are experiencing significant functional impairment. If you haven't already discussed treatment goals around depression specifically, this is the time.

20–27: Severe. The client is endorsing most symptoms at high frequency. Consider whether the current treatment approach is sufficient, whether medication consultation is appropriate, and whether safety planning is needed.

Item 9: the suicidality question

Item 9 asks about "thoughts that you would be better off dead, or of hurting yourself." Any endorsement of this item — even "several days" — warrants a follow-up conversation.

A score of 1 on item 9 doesn't necessarily mean a client is actively suicidal. But it does mean the topic needs to be explored. Many therapists use item 9 as a conversation opener rather than a crisis indicator: "I noticed you marked that you've had some thoughts about being better off dead. Can we talk about that?"

Some outcome tracking tools flag item 9 endorsement automatically, which is useful when you're managing a full caseload and might not review every individual response before a session.

What makes the PHQ-9 useful for therapists

The PHQ-9 has several properties that make it particularly well-suited to ongoing therapy work, as opposed to one-time screening.

It's brief. Nine items, two minutes to complete. Clients can do it in the waiting room or on their phone before a session. The compliance rate stays high because the burden is low.

It's sensitive to change. The PHQ-9 was designed to detect changes in symptom severity over time. A 5-point change is generally considered clinically meaningful — that is, a drop from 17 to 12 represents a real shift, not measurement noise.

It maps to clinical decision-making. The severity bands (mild, moderate, moderately severe, severe) correspond to treatment intensity. When a client's score drops from "moderate" to "mild," that's not just a number — it's a signal that your intervention is working.

It's freely available. The PHQ-9 is in the public domain. No licensing fees, no per-use charges, no permissions needed. You can use it as often as you want with as many clients as you want.

Tracking the PHQ-9 over time

A single PHQ-9 score is useful. A series of PHQ-9 scores over time is transformative.

When you administer the PHQ-9 at regular intervals — say, every two weeks or monthly — you build a longitudinal picture of how the client's depression is responding to treatment. This is where the instrument goes from "screening tool" to "clinical intelligence."

Here's what to look for in the trend data:

Steady decline. The ideal pattern. Scores dropping consistently over time means your treatment approach is working. The client is improving, and you have data to prove it.

Plateau. Scores stabilize but don't continue to drop. This is common after initial improvement and may signal that the current approach has taken the client as far as it can. Time to reassess the treatment plan.

Spike. A sudden increase after a period of stability. Something changed — a life event, a relapse, a medication change, a therapeutic rupture. The spike tells you to ask what happened.

No change. Scores hover in the same range session after session. If you're four or five administrations in and there's no movement, the data is telling you something your sessions might not: this approach isn't working for this client.

Worsening trend. Scores climbing over time, even gradually. This is the pattern therapists most often miss without systematic tracking. By the time you notice the client is doing worse in session, the PHQ-9 may have been signaling it for weeks.

Common mistakes with the PHQ-9

Administering it once and never again. A single score is a snapshot. Without repeated measurement, you can't track change — which is the whole point.

Over-interpreting small changes. A shift from 12 to 11 is not clinically meaningful. Look for 5-point changes or shifts across severity bands before drawing conclusions.

Using it as the only measure. The PHQ-9 measures depression. If your client's primary concern is anxiety, PTSD, or something else, the PHQ-9 alone won't give you the full picture. Pair it with the GAD-7, PCL-5, or other instruments relevant to the presenting concern.

Not discussing results with the client. Clients benefit from seeing their own data. A trend chart showing their PHQ-9 dropping from 19 to 10 over three months is powerful — it's objective evidence that the work is paying off. Share it.

Ignoring item 9. It's easy to focus on the total score and miss a clinically significant response on the suicidality item. Any endorsement needs follow-up, regardless of the total.

The PHQ-9 alongside other instruments

The PHQ-9 works well as part of a broader assessment battery. Common pairings include the GAD-7 for generalized anxiety (which has a nearly identical format and scoring structure), the PCL-5 for PTSD, and the AUDIT for alcohol use.

For clients with comorbid presentations — which is most clients — tracking multiple instruments simultaneously gives you a multidimensional view of how they're doing. Depression improving but anxiety stable? That's a different clinical picture than both improving together.

Putting it into practice

If you're not already using the PHQ-9 routinely, here's a simple way to start.

Pick 5–10 clients on your caseload who you're treating for depression or who have depressive symptoms. Assign them the PHQ-9 to complete before their next session. Review the scores. Note the severity band. Then do it again in two weeks.

After a month, you'll have three data points per client. That's enough to see a trend — and enough to change how you think about session planning.

The therapists who use outcome data consistently report the same thing: they don't want to go back to working without it. Not because the numbers replace clinical intuition, but because they sharpen it.

Theracharts includes the PHQ-9 and 80+ other validated assessments — auto-scored, with trend charts and clinical alerts built in. Get started free.