PHQ-9 questionnaire for symptoms of depression

PHQ-9 (Patient Health Questionnaire) measures how often nine symptoms of a depressive episode have bothered you over the last two weeks. Each question is scored from 0 to 3, so the total runs from 0 to 27 [1].

It is a widely used depression questionnaire in primary care because it is short and because its questions are the diagnostic criteria themselves. The authors released it freely, without requiring permission to reproduce or translate it.

The published cutoffs are 5, 10, 15 and 20 points, separating minimal symptoms from mild, moderate, moderately severe and severe depression [1]. The one that matters most in practice is 10.

At a cutoff of 10 points, the test has a sensitivity of 88% and a specificity of 85% against the clinical interview [2]. That means a score of 10 or above deserves a conversation with a doctor, not that the diagnosis has already been made.

Because depression is roughly twice as common in people with diabetes as in the rest of the population [3]. That is why all patients with diabetes are screened for depressive symptoms at least once a year, and more often in those who have had depression [4].

The link runs both ways. Untreated depression makes day-to-day diabetes care harder: checking blood glucose, taking treatment and going to check-ups. Conversely, diabetes that is hard to control feeds fatigue and discouragement. A two-minute questionnaire is the easiest way to bring the subject up. Anxiety often goes hand in hand with depression, and the GAD-7 questionnaire is used to assess it.

No. The questionnaire measures symptoms, it does not make the diagnosis. Many conditions produce high scores without being depression, from a sleep problem or a thyroid disease to a hard stretch of life. In diabetes, a common cause is diabetes distress, the burden of the daily worries of treatment, which the doctor distinguishes from depression [4]. The diagnosis is made by a doctor, after a conversation with you.

There is, however, one situation in which the score no longer matters. The last question is about thoughts that you would be better off dead or of hurting yourself. If you chose any answer other than "Not at all" there, talk to your doctor or someone close to you today, no matter how small the total is [1]. If you feel you might hurt yourself right now, call the emergency number in your country immediately. These thoughts need urgent care.