User:Rkang101/PHQ-9

Development and History
The Primary Care Evaluation of Mental Disorders (PRIME-MD) was developed in the 1990s by a group of researchers at Columbia University as a tool to screen for mental health problems in individuals seeking medical care. Its development was supported by a grant from the pharmaceutical company Pfizer. The original PRIME-MD evaluated symptoms of depression, anxiety, somatoform disorders, alcohol use, and eating disorders (12 disorders in total). The length of the original assessment limited its feasibility; consequently, a shorter version, consisting of 11 multi-part questions - the Patient Health Questionnaire (PHQ. ) was developed and validated. In addition to the PHQ, a nine-item version to assess symptoms of depression (PHQ-9 ), a seven-item version to assess symptoms of anxiety (GAD-7), and a 15-item version to detect somatic symptoms (PHQ-15 ) have been validated.

Although the PHQ is intended as a comprehensive screening tool and assesses for five symptom clusters (depressive, anxiety, somatoform, alcohol, and eating disorders), the shorter scales (PHQ-9, GAD-7, PHQ-15) can also be given together in order to evaluate multiple symptom domains. Though less commonly used, there are also brief versions of the PHQ-9 and GAD-7 that may be useful as screening tools in some settings. There is also a PHQ-SADS (somatic, anxiety, depressive symptoms) screener designed to be used in primary care settings. In recent years, the PHQ-9 has been validated for use in adolescents, but a version for adolescents (PHQ-A ) was also developed and validated.

Importantly, the PHQ and PHQ-9 have been used in a broad range of populations, including medical populations, epidemiological, geriatric, and adolescent, as screens for depression   .Although these tests were originally designed as self-report inventories they can also be administered by trained health care practitioners. The PHQ, PHQ-9, and GAD-7 have been translated into more than 20 languages; these translated versions are available on the PHQ website (www.phqscreeners.com). Additionally, the measures have been validated in a number of different populations internationally.

Use of the PHQ-15 has been limited primarily to research due to the relatively small number of clinicians who specialize in somatoform disorders. Additionally, several large pharmaceutical companies use the PHQ-15 in their drug trials in the US, Australia, Germany, in the elderly population, and in veterans and active soldiers.

Versions
All versions of the PHQ are free to use, and most versions are available in multiple languages through the parent website: http://www.phqscreeners.com

PRIME-MD
This is the original version of the measure, which has been largely phased out in favor of the new, shorter versions described below.

PHQ
The PHQ includes modules covering depression, anxiety, alcohol use, eating disorders, and somataform disorders. Modules are scored separately to arrive at provisional DSM-IV diagnoses (important to note that this tool is intended as a screening measure and provisional diagnoses should be confirmed by a licensed clinician). The English language version of the PHQ is available here.

PHQ-9
The PHQ-9 is a nine-item scale designed to assess symptoms of depression. Each item is scored on a 0-to-3 point scale (“not at all” to “nearly every day”). Scoring rules may vary by population; one rubric suggests that scores of 5, 10, 25, and 20 correspond to mild, moderate, moderately severe, and severe depression. The English language version of the PHQ-9 is available here.

GAD-7
The GAD-7 is a seven-item scale designed to assess symptoms of anxiety. Each item is scored on a 0-to-3 point scale (“not at all” to “nearly every day”). Cut points of 5, 10, and 15 correspond to mild, moderate, and severe anxiety. The English language version of the GAD-7 is available here.

PHQ-15
The PHQ-15 is a fifteen-item scale to assess the severity of somatic symptoms and the presence of somatoform disorders. The development of the PHQ-15, a subset of the PHQ, is intended to help with the assessment of somatoform disorders. Previous assessments of somatoform disorders required more symptoms for a diagnosis of somatoform disorder, meaning that approximately 10-20% of patients with this disorder were being accurately diagnosed. Furthermore, assessments not only needed to capture more reliable and valid data by focusing on current rather than past symptoms, but also needed to update the “medically unexplained” requirement for these symptoms. It is scored on a 0 (“not at all”) to 2 (“bothered a lot”) scale. Total scores range from 0 to 30, with cutpoints of 5, 10 and 15 corresponding to mild, moderate and severe somatic symptom severity, respectively. The English language version of the PHQ-15 is available here

GAD-2
The GAD-2 is a two-item (first two items of the GAD-7) scale to screen for anxiety.

PHQ-2
The PHQ-2 is a two-item (first two items of the PHQ-9) scale to screen for depression.

PHQ-4
The PHQ-4 is the combination of the PHQ-2 and the GAD-2; it is intended to screen for depression and anxiety. The English language version of the PHQ-4 is available here.

PHQ-8
The PHQ-8 is an eight-item scale developed specifically to screen for depression in American epidemiological populations.

PHQ-A
The PHQ-A is a four module self report to evaluate depression, anxiety, substance use and eating disorders in adolescent primary care patients.

PHQ-SADS
The PHQ-SADS is the combined PHQ-9, GAD-7 and PHQ-15 and is used to screen for depression, anxiety, and somatic symptoms at once. The English language version of the PHQ-SADS is available here.

Limitations
All versions of the PHQ described here are self reports and, consequently, are subject to inherent biases, including social desirability and poor retrospective recall. The influence of these biases can mitigated by following up with a structured or semi-structured interview, the gold standard for diagnostic assessment. The time period assessed by each scale could also be a limitation; the PHQ-9 asks about the last four weeks, whereas the GAD-7 focuses on the past two weeks, and the PHQ asks about various time periods from the last two weeks to the last six months. Depending on the time period in question, this may or may not require a revision (i.e., if you are interested in depression over the last six months, you might alter the instructions), which could impact the validity of the measure. The scoring thresholds recommended are influenced by the samples in which they were validated and correspond with different levels of sensitivity and specificity, which may or may not match well with the intended use of the scale.

Research
See Tables 1 and 2.

Table 1. Norms and reliability statistics* for the primary versions of the PHQ.
Reliability refers to whether the scores are reproducible.

* For ratings benchmarks related to norms and reliability, see https://en.wikiversity.org/wiki/Evidence_based_assessment/Reliability

Table 2. Validity and utility statistics* for the primary versions of the PHQ.
Validity describes the evidence that an assessment tool measures what it was supposed to measure. There are many different ways of checking validity. For screening measures, diagnostic accuracy and discriminative validity are probably the most useful ways of looking at validity.

* For ratings benchmarks related to validity, see https://en.wikiversity.org/wiki/Evidence_based_assessment/Validity