The PHQ-9, or Patient Health Questionnaire-9, is a self-assessment tool that is used by healthcare providers to access the severity of depression in patients. Consisting of 9 objective type questions, this form is used to screen the presence and frequency of depressive symptoms, usually over two weeks in patients.
It serves as a valuable tool for healthcare providers to initiate conversations about mental health, make informed diagnoses, monitor treatment progress, and identify individuals who may require further evaluation or intervention.
The Patient Health Questionnaire-9 (PHQ-9) was developed by a team of researchers led by Dr. Robert L. Spitzer, Dr. Janet B.W. Williams, Dr. Kurt Kroenke, and colleagues. It was first introduced in a 2001 research article titled “Validity of a Brief Depression Severity Measure: The PHQ-9” published in the Journal of General Internal Medicine.
The researchers aimed to create a brief, reliable, and valid self-administered tool for assessing depressive symptoms that could be easily incorporated into clinical practice. The PHQ-9 was developed based on the diagnostic criteria for major depressive disorder from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).
Since its introduction, the PHQ-9 has been widely used in both research and clinical settings as a screening and diagnostic tool for depression and has become a commonly used instrument for assessing depressive symptoms due to its brevity and effectiveness.
The questionnaire asks individuals to rate the frequency of their symptoms on a scale of “Not at all,” “Several days,” “More than half the days,” or “Nearly every day.”
The responses for each of the questions are associated with scores from 0 to 3, wherein the higher scores indicate more severe symptoms. The total score is calculated by summing the values of each response, ranging from 0 to 27. The healthcare professionals then interpret these scores to assess the severity of depression and determine appropriate treatment options.
The higher the score more severe the depressive symptoms in the patient, for a score range between 20-27 immediate initiation of psychological therapy is usually recommended
A PHQ-9 has contributed significantly towards the assessment and development of mental health. It helps healthcare professionals understand and interpret the patient’s mental health, identify their risk of depression, suggest specific treatments, track progress, and determine appropriate interventions.