PHQ-4 Calculator

The Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief four-item self-report screening tool that combines the PHQ-2 (depression) and GAD-2 (anxiety) into a single instrument. Developed by Kroenke, Spitzer, Williams, and Lowe, and published in Psychosomatics in 2009, the PHQ-4 provides simultaneous screening for the two most common mental health conditions — depression and anxiety — in under two minutes.

The PHQ-4 consists of four items: two assessing core depressive symptoms (loss of interest, depressed mood) and two assessing core anxiety symptoms (nervousness, uncontrollable worry). Each item is scored from 0 ("Not at all") to 3 ("Nearly every day"), yielding a total score between 0 and 12. The instrument is freely available in the public domain.

The PHQ-4 was developed by combining the two validated ultra-brief screeners — the PHQ-2 and GAD-2 — into a single instrument. Kroenke and colleagues validated it in a large primary care sample, demonstrating that the four-item combination retained strong screening properties for both depression and anxiety.

The original validation study showed excellent internal consistency (Cronbach's alpha of 0.81) and a strong correlation with functional impairment. Higher PHQ-4 scores were associated with significantly more disability days, clinic visits, and difficulty in performing daily activities.

The PHQ-4 can be interpreted both as a total score (for overall psychological distress) and as two subscales: a depression subscale (items 1-2, the PHQ-2) and an anxiety subscale (items 3-4, the GAD-2). This dual structure allows clinicians to screen for both conditions simultaneously while still identifying which domain is predominantly affected.

The PHQ-4 uses the same four-point Likert scale as the PHQ-9 and GAD-7:

0 = Not at all 1 = Several days 2 = More than half the days 3 = Nearly every day

Total scores range from 0 to 12. Published severity thresholds are:

0-2: Normal range 3-5: Mild — monitoring recommended 6-8: Moderate — clinical follow-up recommended 9-12: Severe — comprehensive assessment recommended

Subscale scoring is also available: Depression subscale (items 1-2): Score of 3 or above suggests further depression evaluation warranted Anxiety subscale (items 3-4): Score of 3 or above suggests further anxiety evaluation warranted

The total score provides an index of overall psychological distress, while the subscales help identify whether depression, anxiety, or both may require further evaluation.

The PHQ-4 is particularly valuable in settings where very brief combined screening for depression and anxiety is needed. Its primary applications include:

Routine screening in primary care, where it can be embedded in patient intake forms or annual health checks. Its four-item format minimises respondent burden while covering the two most prevalent mental health conditions.

Emergency departments and acute care, where rapid identification of psychological distress is important but time is extremely limited.

Population health surveys and epidemiological research, where the PHQ-4 provides an efficient measure of psychological distress burden.

Stepped-care models, where positive PHQ-4 screens lead to administration of the full PHQ-9 and/or GAD-7 for severity assessment and treatment monitoring.

The PHQ-4's strength lies in its efficiency as a combined screener. For ongoing severity monitoring, the full PHQ-9 and GAD-7 are recommended.

In Australia, the PHQ-4 is used in general practice, hospital, and community health settings as a rapid combined screen for depression and anxiety. While the K-10, PHQ-9, and GAD-7 remain the primary instruments recommended under the Better Access initiative, the PHQ-4 serves as a practical initial screen in time-constrained environments.

The instrument is particularly useful in Australian general practice, where time pressures during consultations can make longer instruments challenging to administer. A positive PHQ-4 screen can prompt the GP to proceed with more detailed assessment using the PHQ-9, GAD-7, or K-10.

The PHQ-4's dual focus on depression and anxiety aligns well with Australian epidemiological data showing high rates of comorbidity between these conditions in the Australian population.