PHQ-9

The PHQ-9 (Patient Health Questionnaire-9) takes directly from the nine symptoms of a major depressive episode in the DSM. For each one, it assesses how often it has occurred over the past two weeks.

The total score ranges from 0 to 27 and is divided into severity bands (minimal, mild, moderate, moderately severe, severe).

Short, reliable and free to use, the PHQ-9 is one of the most widely employed depression screening tools in the world, in primary care as well as in research.

Its ninth item addresses suicidal thoughts: a positive response warrants immediate attention, regardless of the total score.

A high score does not automatically mean "depression": fatigue, grief, physical illness or another disorder can influence the responses. The diagnosis rests with a health professional.