PHQ-9

The Patient Health Questionnaire (PHQ) is a self-administered version of the Primary Care Evaluation of Mental Disorders diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the nine diagnostic criteria for major depression in Diagnostic and Statistical Manual Fourth Edition as ‘0’ (not at all) to ‘3’ (nearly every day) [1]. The nine items cover experience of pleasure, feeling down, sleep disruption, energy levels, appetite, feeling a failure, trouble concentrating, speaking slowly or being fidgety and having negative thoughts around suicide or self-harm over the previous 2 weeks. The PHQ-9 can be self-administered or administered by a clinician. At an initial visit the PHQ-9 can be used to assist with diagnosis and identification of problem symptoms. At the follow-up visit, the PHQ-9 is used to measure treatment response and identify specific symptoms that are not responding. Thus the questionnaire is a useful tool to assist clinicians in diagnosing depression and monitoring the response to treatment. It is also a reliable and valid measure of depression severity. These characteristics plus its brevity also make the PHQ-9 a useful clinical and research tool. Some clinicians use the first two items of the PHQ-9 (‘Over the last 2 weeks, how often have you been bothered by any of the following problems? 1. Little interest or pleasure in doing things and 2. Feeling down, depressed or hopeless?’) as an initial screen for depression. If the patient responds affirmatively to either of these two items, the remaining seven items are asked. This can be an efficient way to screen large groups of patients to improve detection of undiagnosed depression [2]. Research has shown that certain scores on the PHQ-9 are strongly correlated with a subsequent diagnosis of major depression although not everyone with an elevated PHQ-9 is certain to have major depression. The PHQ-9 is intended as a tool to assist clinicians with identifying and diagnosing depression but is not a substitute for diagnosis by a trained clinician [3]. The questionnaire is free to use and is widely used in general practice. The trademark is held by the pharmaceutical company Pfizer who also own the copyright for the use of the PHQ and PHQ-9. Its terms of use can be found online at www.phqscreeners.com/terms.aspx. Use is free within the terms of use and the PHQ-9 can be downloaded from www.patient.co.uk/doctor/patient-health-questionnaire-phq-9. The PHQ-9 is often chosen because (i) it is shorter to use than other depression rating scales, (ii) it can be administered not only by clinicians and self-administered but also by telephone, (iii) it facilitates the diagnosis of major depression and provides an assessment of symptom severity, (iv) it has been proven to be effective in a geriatric population [4] and (v) it is also well validated and documented in a variety of populations. The validity of the questionnaire has been assessed against an independent structured mental health professional interview. PHQ-9 score ≥10 had a sensitivity and a specificity of 88% each for major depression [5,6]. It has also been specifically validated for use over the telephone [7] and in the primary care setting [6]. PHQ-9 is one of many depression rating scales that have been validated for use in primary care and other settings. Instruments vary by whether they are self-reported or interviewer reported and applicable to patients with cognitive or language barriers. The Geriatric Depression Scale [8] self-report instrument was developed by researchers at Stanford University and has been studied in multiple settings. There is a five-item version and a 15-item version of this measure. (The 15-item measure has excellent psychometric properties compared with a structured diagnostic instrument in a sample of functionally impaired, cognitively intact, community-dwelling primary care patients.) Apps exist for Android and iPhone. Further details can be found at http://www.stanford.edu/~yesavage/GDS.html. The Center for Epidemiologic Studies Depression Scale [9] is one of the most common instruments applied in community studies and also used in primary care settings. The questionnaire and further details can be found at http://cesd-r.com/. Cornell Scale for Depression in Dementia [10] incorporates both observer- and informant-based information and is helpful in evaluating cognitively impaired patients (such as those with dementia) for depression. The questionnaire and scoring guidelines can be found at http://www.scalesandmeasures.net/files/files/The%20Cornell%20Scale%20for%20Depression%20in%20Dementia.pdf.