PHQ-9: nine questions that map onto the depression criteria
Two weeks. That is the window the PHQ-9 asks about, not today and not "lately" in general. Nine items, each one a symptom the DSM lists for major depression, each rated 0 to 3 by how often it showed up.
Kroenke, Spitzer and Williams published the nine-item version in 2001 out of the PRIME-MD project. The items run from loss of interest and low mood through sleep, appetite and concentration to item 9, which asks about thoughts of being better off dead.
How the score works
Add the nine ratings and you get a total between 0 and 27. Nothing is reverse-scored, so it is one of the easier screens to score by hand.
| Total | Band |
|---|---|
| 0-4 | None or minimal |
| 5-9 | Mild |
| 10-14 | Moderate |
| 15-19 | Moderately severe |
| 20-27 | Severe |
Item 9 gets its own rule: any score above zero is worth following up, whatever the total says.
Where the cutoff of 10 comes from
Kroenke's validation used structured interviews by mental health professionals as the reference standard, in two samples of roughly 3,000 each, one in primary care and one in obstetrics and gynaecology. At 10 or above, sensitivity and specificity both came out at 88%, with an area under the ROC curve of 0.95. That symmetry is why 10 became the default.
Likelihood ratios sharpen the reading. A score in the 10-14 band multiplies the odds of major depression by about 2.6. In the 15-19 band it is 8.4, and in the 20-27 band it is 36.8. Higher scores do not simply mean "more". They change how far the result should move your thinking.
Some clinics screen at 5 to miss fewer people. That is a deliberate trade: fewer missed cases, more false alarms.
Reliability
Internal consistency was .89 in the primary care sample and .86 in the obstetrics sample. Retesting within 48 hours gave r = .84, with means that barely moved (5.08 to 5.03). Stability that high over two days mostly tells you the questions get read the same way twice.
What a score is not
A total is a count of symptoms, not a diagnosis. A major depressive episode requires five or more of the nine criteria for more than half the days over two weeks, and at least one of them has to be low mood or loss of interest. A questionnaire can count symptoms. It cannot tell whether they come from a medical condition, a medication or bereavement, and it cannot see how much they interfere with your life. If your score lands in the moderate band or above, or if item 9 is above zero, that is a reason to talk to a clinician rather than a reason to conclude anything on your own. This page is not a diagnosis and does not replace one.