PHQ-9: Patient Health Questionnaire-9

Overview

The PHQ-9 is a nine-item adult depression screen covering the past two weeks. Survey Doctor adds nine frequency ratings for a total from 0 to 27 and reports five symptom bands. The score describes current symptom burden. It does not diagnose depression, explain its cause, or decide treatment.

Context still matters.

Who should take this assessment?

The PHQ-9 can support an adult screening or symptom review when low mood, loss of interest, sleep changes, low energy, appetite changes, concentration problems, changes in movement, or thoughts of death or self-harm are concerns.

The adult English form is the version audited for Survey Doctor. This page does not establish use for adolescents or the PHQ-A. Youth versions need separate evidence for their exact wording, population, and administration.

What to expect

The official English form asks nine questions about the past two weeks. Each answer uses the same frequency scale:

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

All nine answers are required in the native Survey Doctor workflow. Completing the questionnaire usually takes only a few minutes, but take enough time to consider the full two-week period.

Score interpretation

Nine answers. One sum. There is no weighting or reverse scoring, and the original validation study supports the five boundaries shown here.

These supported bands are descriptive. They do not prescribe care, and a low band never means that someone should stop existing care or avoid asking for help.

A boundary is not a cliff. One point can move a result into another band without showing a sudden clinical change, and the score cannot explain why symptoms occurred.

For a plain-language walkthrough, see what your PHQ-9 score means.

Item 9 and safety

Item 9 asks about thoughts of being better off dead or hurting yourself. Any endorsement matters. It needs prompt, direct follow-up regardless of the total, but remains a safety signal rather than a complete suicide risk assessment.

If you need help now. In the US, Call 988 or text 988. Call 911 if you are in immediate danger. Outside the US, contact your local emergency number or find support in your country.

Optional functional companion

Published PHQ-9 materials can include an unscored question about how symptoms affect work, home responsibilities, and relationships. That answer is separate from the 0 to 27 score.

Survey Doctor shows this optional companion when any scored symptom is above zero. It saves the response separately and never adds it to the symptom total. An all-zero result does not show the question.

Historical, manual, and imported rows without companion data mean it was not collected. Do not infer a functional response from the symptom score.

What the questions measure

The nine items cover interest or pleasure, low mood, sleep, energy, appetite, feelings about yourself, concentration, movement or restlessness, and thoughts of death or self-harm.

These areas parallel depression symptom criteria. The questionnaire does not establish whether the symptoms form a disorder. It also does not rule out bipolar conditions, grief, physical illness, medication effects, substance effects, or another explanation.

The two-week window is deliberate. It provides a current symptom snapshot but does not show long-term course, recurrence, or what happened outside that period.

Using repeated scores

Complete native PHQ-9 results can be compared over time when the form and administration conditions remain similar. Look at the pattern. A change in item 9 matters independently of the overall direction.

There is no single point change, percentage change, remission rule, or retest interval that applies in every setting. Published approaches vary by population and purpose. Use an explicit, source-backed protocol when applying one.

Native score history can show the separately stored companion response when it was collected. It adds context but does not change the score or trend. Historical, manual, and imported rows without companion data mean it was not collected.

Some imported historical PHQ summaries are not native PHQ-9 results. They may include a tenth functional response in the total, and only the summary score was retained. Survey Doctor keeps those values separate from native bands and trends because the original answers cannot be recovered.

Important limitations

• The total cannot diagnose depression or identify its cause.
• The functional companion is optional, appears only after a scored symptom is endorsed, and remains separate from the total.
• Physical illness, medication effects, substances, and life events can affect answers.
• A score-only manual record cannot show item 9 safety status.
• This audited implementation establishes the adult English form, not an adolescent version.
• A low score does not override a person's concerns or current care plan.

Evidence and population limits

The original PHQ-9 validation included 6,000 adult outpatients from eight primary care and seven obstetrics-gynecology clinics. A subset of 580 completed an independent structured interview with a mental health professional.

At a threshold of 10, sensitivity and specificity for major depression were both 88% in that interview subset (Kroenke et al., 2001). Those figures belong to the study population and method. They do not turn 10 into a diagnosis or guarantee the same performance in every setting, language, or age group.

Related assessments

PHQ-2: Patient Health Questionnaire-2:
A two-item depression screen drawn from the first two PHQ-9 items

GAD-7: Generalized Anxiety Disorder 7-item:
A seven-item screen for generalized anxiety symptoms

PHQ-15: Patient Health Questionnaire-15:
A questionnaire about physical symptom burden