Depression Screening (PHQ-9)

The PHQ-9 is the 9-item Patient Health Questionnaire, developed by Spitzer, Kroenke and Williams in the late 1990s and validated across thousands of primary care patients. It maps directly onto the nine symptoms of major depressive disorder in the DSM, asking how often each has bothered you in the last two weeks, scored 0 (not at all) to 3 (nearly every day). Total scores run 0 to 27.

It is the standard depression screen used by NHS GPs, IAPT services, employee assistance programmes, and health insurers worldwide. The tool sits in the public domain because Pfizer released it for unrestricted use, which is why the same nine questions appear on millions of clipboards every year.

Standard cut-offs are 5 for mild, 10 for moderate, 15 for moderately severe, and 20 for severe depression. A score of 10 or above is the point at which the original validation paper found acceptable sensitivity and specificity for major depression, and it is the threshold most NHS services use to consider treatment.

A high score is not a diagnosis. It is a flag that says "go talk to someone qualified". A low score is also not a clean bill of health, particularly if specific items (poor sleep, low energy) are still bothering you in isolation. The questionnaire was built to start a conversation, not finish one. Question 9 about thoughts of self-harm is scored separately and is taken seriously regardless of the rest of the total.

The most common reason is the obvious one: you have been feeling rough for weeks and want some structure to the question of whether to book a GP appointment. The second most common is tracking. People already in therapy or on antidepressants often retake the PHQ-9 every few weeks to spot whether things are actually improving, since the slow nature of recovery can hide week-on-week change.

The third use, and one we feel strongly about, is family members trying to gauge concern. If someone you love has been off and you do not know how worried to be, the PHQ-9 is a reasonable conversation-starter, but it is not a substitute for asking them directly how they are. The [GAD-7 anxiety screener](/anxiety-screening-gad7) is often used alongside it because anxiety and depression frequently co-occur.