The PHQ-2 is the first two questions of the PHQ-9, covering low mood and loss of interest. It works as a first step that decides who answers the other seven. The PHQ-9 adds severity bands and an item on thoughts of death or self-harm. Neither questionnaire diagnoses depression.
Used in sequence, the two questionnaires ask fewer people to complete all nine items, at a measurable cost in missed cases. This page compares the two and gives the published figures. For running the sequence in a clinic, including billing, see two-step depression screening.
How the two questionnaires relate
Both come from the Patient Health Questionnaire by Kroenke, Spitzer and Williams. The PHQ-9 is its depression module and scores each of the nine DSM-IV criteria for major depression from 0 to 3 (Kroenke et al., 2001). The PHQ-2 keeps the first two items (Kroenke et al., 2003).
| Feature | PHQ-2 | PHQ-9 |
|---|---|---|
| Items | 2 | 9 |
| Time frame | Past two weeks | Past two weeks |
| Score range | 0-6 | 0-27 |
| Usual cutoff | 3 or more is a positive screen | 10 or more |
| Severity bands | No | Five descriptive bands |
| Item on thoughts of death or self-harm | No | Yes (item 9) |
| Functional question | No | Optional, unscored, stored apart from the total |
The two PHQ-2 items ask how often the person has had little interest or pleasure in doing things, and how often they have felt down, depressed or hopeless. Those are the two core symptoms of depression. According to the National Institute of Mental Health, one of the symptoms behind a depression diagnosis must be a depressed mood or a loss of interest or pleasure. A low PHQ-2 score still cannot rule depression out, because it records how often two symptoms were reported and is not a clinical assessment.
How the two-step sequence works
- Everyone in the screened group completes the PHQ-2.
- A score at or above the chosen cutoff leads to the PHQ-9. Because the PHQ-2 items are PHQ-9 items 1 and 2, the person can keep those answers and complete items 3 to 9, or complete all nine again. Do not add a PHQ-2 total to a PHQ-9 total, because the PHQ-9 already contains those two answers.
- A score below the cutoff ends the routine screen. Symptoms, history, clinician concern or a safety issue can still justify the PHQ-9 or an interview.
How accurate each one is
Published accuracy depends on the study and on the interview used as the reference standard. The original validation studies and a 2020 meta-analysis give different figures for the same cutoffs, so quote each with its source.
The original validation studies analyzed questionnaires from 6,000 patients in 8 primary care and 7 obstetrics-gynecology clinics. A sample of 580 also had an independent structured interview with a mental health professional, which served as the reference standard.
In 2020, Levis and colleagues pooled individual participant data from 100 studies with 44,318 participants (Levis et al., 2020). The figures below come from the 48 studies (11,703 participants) that used semistructured diagnostic interviews.
| Source and reference standard | Cutoff | Sensitivity | Specificity |
|---|---|---|---|
| Kroenke et al. (2003): 580 patients, structured interview | PHQ-2 ≥3 | 83% | 92% |
| Kroenke et al. (2001): 580 patients, structured interview | PHQ-9 ≥10 | 88% | 88% |
| Levis et al. (2020): 48 studies, semistructured interview | PHQ-2 ≥3 | 72% | 85% |
| Levis et al. (2020): 48 studies, semistructured interview | PHQ-2 ≥2 | 91% | 67% |
The Kroenke 2003 figures are the ones reported in the paper's abstract. The paper's Table 2 lists 82.9% sensitivity and 90.0% specificity at the same cutoff. Levis et al. also found that PHQ-2 sensitivity was significantly lower in studies that used fully structured interviews as the reference.
What two-step screening misses
The PHQ-2's sensitivity is measured against a diagnostic interview, not against the PHQ-9. So the PHQ-2 figure alone cannot tell you how many cases the sequence loses compared with giving everyone the PHQ-9.
Levis et al. (2020) tested that comparison directly. They used 44 studies with 10,627 participants that had a semistructured interview and both questionnaires. Of those participants, 1,361 had major depression on interview.
| Approach | Completed the full PHQ-9 | Sensitivity | Specificity |
|---|---|---|---|
| PHQ-9 ≥10 for everyone | 100% | 86% | 85% |
| PHQ-2 ≥2, then PHQ-9 ≥10 | 43% | 82% | 87% |
| PHQ-2 ≥3, then PHQ-9 ≥10 | 25% | 70% | 91% |
With a PHQ-2 gate of 2, the sequence identified 82% of interview-diagnosed major depression, against 86% for the PHQ-9 alone. The authors found that difference was not statistically significant, and the sequence cut the number of full PHQ-9s needed by 57%. With a gate of 3, a quarter of participants completed the PHQ-9 and sensitivity fell to 70%. These were research samples. The share who screen positive in a clinic depends on how common depression is there.
Choosing the PHQ-2 cutoff
Kroenke et al. (2003) identified 3 as the optimal PHQ-2 cutpoint for screening in their data. When the PHQ-2 is a gate to the PHQ-9, the meta-analysis points to 2. Levis et al. concluded that a PHQ-2 of 2 or more followed by a PHQ-9 of 10 or more had similar sensitivity to the PHQ-9 alone and higher specificity. They added that more research is needed on the clinical value of the combined approach. A gate of 3 sends fewer people on to the PHQ-9 and misses more cases.
Set the cutoff in the screening protocol before screening starts, and apply it the same way for every patient.
When to use the PHQ-9 directly
Skip the PHQ-2 step in these situations:
- Depression is already the question. If a patient reports depressive symptoms, or depression is being treated or monitored, start with the PHQ-9. The two-step sequence is for screening people who have not raised the concern.
- You need to follow change. The PHQ-9 gives nine item scores and a 0 to 27 total to compare across visits. In a study of 434 older adults in the IMPACT trial, a five-point PHQ-9 difference was the estimated minimum clinically important change. That supports a review signal in a similar context, not a universal response rule. Tracking PHQ-9 scores over time covers comparing results.
- The service needs a safety item. The PHQ-2 has no question about thoughts of death or self-harm. PHQ-9 item 9 asks about them, but one item is not a suicide risk assessment. Any answer above zero needs same-day follow-up under the practice's safety protocol, whatever the total. The USPSTF found the evidence insufficient to weigh the benefits and harms of screening adults for suicide risk. Follow your organization's own risk assessment protocol.
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If you are checking yourself
Both questionnaires are screening tools. A score can show that it is worth talking to a doctor or therapist, but only a full assessment can say whether you have depression.
- For a quick first check, the PHQ-2 is two questions. A score below 3 does not rule out depression if you are still worried. What your PHQ-2 score means explains the result.
- If you are already concerned, or have been treated for depression before, take the PHQ-9 instead. It covers nine symptoms and gives a severity band. What your PHQ-9 score means explains each band.
- If your PHQ-2 score is 3 or higher, complete the PHQ-9 and book an appointment. Bring both scores with you.
- To track how you feel, use the PHQ-9. Each attempt asks about the past two weeks, so retaking it within two weeks repeats part of the same period.