Clinical Screening Questionnaires
Published October 11, 2026 · Last updated October 11, 2026
How the PHQ-9, GAD-7, Epworth Sleepiness Scale, and STOP-BANG questionnaire screen for depression, anxiety, daytime sleepiness, and obstructive sleep apnoea risk — and why a screening result is not a diagnosis.
Screening questionnaires turn a short set of self-reported or observed items into a severity band or risk estimate. They are widely used in primary care and specialist clinics because they are quick, validated, and repeatable, and because they can be tracked over time. The library contains four: the PHQ-9, the GAD-7, the Epworth Sleepiness Scale, and the STOP-BANG questionnaire.
This guide describes what each instrument screens for and why a positive result is a prompt for further assessment rather than a diagnosis.
Depression: the PHQ-9
The PHQ-9 grades the severity of depressive symptoms over the previous two weeks using nine items aligned with the DSM criteria, and it also identifies possible suicidal ideation. It is validated as a brief depression severity measure and is commonly used to monitor treatment response.
Anxiety: the GAD-7
The GAD-7 grades the severity of generalised anxiety symptoms over the previous two weeks. It was developed as a brief measure for assessing generalised anxiety disorder and has been studied in primary care populations.
Daytime sleepiness: the Epworth Sleepiness Scale
The Epworth Sleepiness Scale quantifies the general level of daytime sleepiness across everyday situations, distinguishing pathological sleepiness from normal variation. It supports the evaluation of sleep disorders such as obstructive sleep apnoea and narcolepsy.
Obstructive sleep apnoea risk: STOP-BANG
The STOP-BANG questionnaire estimates the pre-test probability of obstructive sleep apnoea from history and physical findings, guiding the need for objective sleep testing. It is designed as a rapid screen and has high sensitivity but more moderate specificity.
Screening is not diagnosis
These instruments estimate the probability or severity of a condition; they do not establish a diagnosis, and a positive screen warrants further clinical evaluation. Scores are most informative when repeated and read as a trend alongside the clinical picture, not as a single standalone result.
Calculators in this guide
Related guides
References
- Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613.
- Spitzer RL, Kroenke K, Williams JB. Validation and utility of a self-report version of PRIME-MD: the PHQ primary care study. JAMA. 1999;282(18):1737-1744.
- Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092-1097.
- Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep. 1991;14(6):540-545.
- Chung F, Yegneswaran B, Liao P, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology. 2008;108(5):812-821.