PHQ-9 — Patient Health Questionnaire (9 items)
The PHQ-9 is a 9-item depression screener developed by Kroenke, Spitzer & Williams (2001). It asks how often, over the past two weeks, the respondent has been bothered by each of the nine DSM depression symptom criteria. Scores are reported with published severity bands and an empirical population percentile.
Minimal (0–4)
Few or no depressive symptoms reported.
Mild (5–9)
Mild symptom levels; watchful waiting or re-screening may be appropriate.
Moderate (10–14) / Moderately severe (15–19)
Clinically relevant symptom levels warranting professional evaluation.
Severe (20–27)
Severe symptom levels; professional assessment is strongly recommended.
At a glance
About the PHQ-9
The PHQ-9 is the depression module of the Patient Health Questionnaire, developed by Kroenke, Spitzer, and Williams as a brief self-report screen for use in primary care. Each of the nine items maps directly onto one of the DSM symptom criteria for major depressive disorder and is rated on a 4-point frequency scale from "not at all" (0) to "nearly every day" (3).
The summed total (0–27) is interpreted against the published severity bands: 0–4 minimal, 5–9 mild, 10–14 moderate, 15–19 moderately severe, and 20–27 severe. The PHQ-9 is a screening instrument, not a diagnostic tool — elevated scores identify people who may benefit from a fuller clinical evaluation. The instrument is in the public domain and is administered here verbatim with attribution.
Kroenke, K., Spitzer, R. L., & Williams, J. B. W. (2001). The PHQ-9: Validity of a brief depression severity measure. Journal of General Internal Medicine, 16(9), 606–613.How the percentile is calculated
Alongside the severity band, PHQ-9 results on this platform show an empirical population percentile. Screener scores are strongly skewed — most people in the general population score near zero — so a percentile computed from a mean and standard deviation under a normality assumption would be misleading. Instead, the percentile is read directly from a published cumulative distribution table: the percentage of a general-population reference sample scoring at or below each raw total.
The reference table comes from Kliem and colleagues (2024), who report cumulative percentages for every PHQ-9 total score in a German general-population sample (N = 2,519; Cronbach's α = 0.90). A percentile of 94, for example, means 94% of that reference sample scored at or below the same total. The source does not publish a scale-level standard deviation, so no confidence range is shown for the PHQ-9 percentile.
The reference sample is German. General-population symptom distributions differ between countries, so the percentile is labeled with its country of origin and should be read as standing relative to that specific reference population, not a universal norm. The severity bands above are independent of the percentile and follow the original validation study.
Kliem, S., et al. (2024). Norm values of the Patient Health Questionnaire-9 based on a representative German sample. Frontiers in Psychiatry, 15:1483782 (open access, CC BY).How it is administered here
The PHQ-9 is a clinical screener on this platform: it is delivered to a respondent through a secure link generated by a clinician, who then reviews the scored result. It is not self-administered from the public catalog. Clinicians can administer it from the clinician portal; the full item text, psychometric summary, and citations are on the PHQ-9 scale page.