PHQ-9 Score

In addition to the severity score, the PHQ-9 can be used as a provisional diagnostic tool using a categorical algorithm. A “provisional diagnosis” of major depressive disorder can be considered if:

• At least 5 of the 9 items are scored ≥2 (“more than half the days”), AND
• At least one of the positive items is item 1 (anhedonia) or item 2 (depressed mood)

This mirrors the DSM-5 diagnostic criteria requiring five or more symptoms (including depressed mood or anhedonia) present for at least two weeks. However, the diagnostic algorithm has lower sensitivity than the ≥10 cutoff score and is not recommended as the sole method of screening. It is most useful when a clinician wants to check whether the PHQ-9 symptom pattern is consistent with a formal DSM-5 diagnosis.

Note: Item 9 (suicidal ideation) counts towards the criterion count — a score of ≥2 on item 9 counts as a positive criterion. However, item 9 should always be assessed clinically regardless of its contribution to the algorithm.

The PHQ-2 consists of just the first two items of the PHQ-9 — anhedonia and depressed mood — scored identically (0–3 each, total 0–6). At a cutoff of ≥3, it has a sensitivity of approximately 83% and specificity of 92% for major depression, making it a useful rapid pre-screen.

A common clinical workflow is to administer the PHQ-2 first and then proceed to the full PHQ-9 only if the PHQ-2 score is ≥3. This two-stage approach reduces screening burden while maintaining acceptable diagnostic accuracy. The PHQ-2 is recommended by several guidelines (including the USPSTF) as an initial screening step in primary care.

However, the PHQ-2 alone cannot grade severity, monitor treatment response, or identify the specific symptom domains affected — tasks for which the full PHQ-9 is needed.

Several validated tools exist for depression screening and severity assessment. The choice depends on the clinical setting, purpose, and available time:

• BDI-II (Beck Depression Inventory-II): 21 items, self-report. Well validated and widely used in research and clinical psychology. More comprehensive than the PHQ-9 but longer to administer. Copyrighted and requires purchase, unlike the PHQ-9 which is freely available.
• HAM-D (Hamilton Depression Rating Scale): 17–21 items, clinician-rated. Considered a reference standard in clinical trials. Requires training to administer reliably. Not practical for routine primary care use but important in psychiatric and research settings.
• GAD-7 (Generalised Anxiety Disorder-7): Not a depression tool, but highly relevant because anxiety and depression frequently co-occur. The PHQ-9 and GAD-7 are often administered together for a combined assessment of the two most common mental health conditions in primary care.

The PHQ-9’s advantages are its brevity, free availability, dual use for screening and monitoring, direct correspondence to DSM criteria, and extensive cross-cultural validation. Its main limitation is that it does not assess bipolar disorder, psychotic features, or substance use-related mood symptoms.

The PHQ-9 is central to measurement-based care (MBC) — a systematic approach to psychiatric treatment in which validated rating scales are administered at each visit to track symptom trajectory and inform treatment decisions. Evidence from studies such as STAR*D demonstrates that MBC improves depression outcomes compared to standard care.

Key monitoring targets:

• Response: ≥50% reduction from baseline score (e.g. baseline 18 → ≤9)
• Remission: score <5
• Clinically meaningful change: ≥5-point change from previous score
• Monitoring interval: every 2–4 weeks during acute treatment, extending to 4–8 weeks during maintenance

If the PHQ-9 score has not decreased by ≥5 points after 6–8 weeks of adequate-dose antidepressant therapy, clinicians should reassess the diagnosis, check adherence, consider dose optimisation, augmentation, switching, or adding psychotherapy. Persistent high scores despite adequate treatment should prompt consideration of treatment-resistant depression and specialist referral.

The 10th question — “How difficult have these problems made it for you to do your work, take care of things at home, or get along with other people?” — is not included in the PHQ-9 score but provides essential clinical context. A patient may score 12 on the PHQ-9 (moderate) but report “not at all difficult” functional impairment, suggesting reasonable coping despite symptoms. Conversely, a patient scoring 8 (mild) who reports “extremely difficult” impairment may require more active intervention than the score alone would suggest.

Functional impairment is a core criterion for major depressive disorder in the DSM-5 — symptoms must cause “clinically significant distress or impairment in social, occupational, or other important areas of functioning.” The functional impairment question helps bridge the gap between symptom count and clinical significance.

A PHQ-9 score of 15 does not mean the patient has major depressive disorder. It means the patient reports a moderately severe burden of depressive symptoms over the past two weeks. These symptoms could reflect major depression, an adjustment disorder, grief, bipolar depression, depression secondary to a medical condition, medication side effects, or substance use. A positive screen is a starting point for clinical assessment, not an endpoint.

Always follow a positive PHQ-9 screen with a clinical interview that evaluates symptom duration, functional impairment, psychiatric history, medical causes, substance use, and differential diagnosis. The PHQ-9 score informs the conversation — it does not replace it.

Item 9 asks about thoughts of being better off dead or of self-harm. Any positive response (≥1) requires immediate clinical follow-up — regardless of the total score. A patient with a PHQ-9 total of 6 (mild) who endorses item 9 at a frequency of “several days” has disclosed suicidal ideation and needs a safety assessment just as urgently as a patient scoring 25.

The PHQ-9 is not a suicide risk assessment tool. A positive item 9 should trigger a structured evaluation of suicidal ideation (frequency, intensity, duration), intent, plan, access to means, protective factors, and history of prior attempts. Document the assessment and management plan, and ensure the patient’s safety before the consultation ends.

The PHQ-9 measures depressive symptoms but does not screen for mania or hypomania. Patients with bipolar depression may score highly on the PHQ-9 and appear indistinguishable from unipolar depression on the questionnaire alone. Starting an antidepressant without a mood stabiliser in a patient with unrecognised bipolar disorder can precipitate a manic episode.

Before initiating antidepressant treatment based on a positive PHQ-9, always ask about: previous episodes of elevated mood, decreased need for sleep with increased energy, grandiosity, pressured speech, impulsive behaviour, family history of bipolar disorder, and previous adverse reactions to antidepressants (e.g. “feeling wired” or switching to mania). Consider using the Mood Disorder Questionnaire (MDQ) as a screening adjunct.

The functional impairment question is frequently overlooked because it does not contribute to the total score. However, it is one of the most clinically useful components of the PHQ-9. DSM-5 requires functional impairment for a diagnosis of major depressive disorder — a patient with five depressive symptoms but no functional impact does not meet diagnostic criteria.

Functional impairment also predicts treatment need and prognosis. A patient reporting “extremely difficult” impairment at a score of 10 likely needs more aggressive treatment than a patient at the same score reporting “not at all difficult.” Always review this question alongside the total score.

Four of the nine PHQ-9 items assess somatic symptoms — sleep disturbance (item 3), fatigue (item 4), appetite change (item 5), and psychomotor change (item 8). In patients with chronic medical conditions, these symptoms may be attributable to the medical illness rather than depression, potentially inflating the PHQ-9 score.

There is no universally accepted correction for somatic overlap. Some clinicians use the cognitive-affective subscale (items 1, 2, 6, 7, 9) as a more specific depression indicator in medically complex patients. Others interpret the total score in context, recognising that even if somatic symptoms are partly medical, the patient’s overall symptom burden still affects wellbeing and may benefit from treatment.