Key messages
• The GAD-7 and GAD-2 questionnaires alone cannot be used to diagnose or rule out an anxiety disorder.
• However, they provide an indication of whether an anxiety disorder may be present.
• The interpretation of a "negative" or "positive" questionnaire finding of an individual depends on the context.
What are anxiety disorders?
'Anxiety disorder' is an umbrella term which refers to mental health conditions including (but not limited to):
• generalised anxiety disorder: when someone experiences excessive anxiousness for most days over six months, difficulty controlling worry, plus at least three of six symptoms: restlessness, fatigue, difficulty concentrating, irritability, muscle tension, and sleep disturbance;
• social phobia: a strong fear of being judged, embarrassed, or humiliated in social or performance situations;
• panic disorder: repeatedly experiencing unexpected and intense periods of fear or discomfort, which may involve a variety of physical and emotional symptoms.
Why is an early diagnosis of anxiety disorders important?
Anxiety disorders are common and often remain undetected, even in people for whom treatment can be regarded as necessary. Not recognising an anxiety disorder when it is present (false negative) means that you miss the opportunity of timely treatment with medicine, psychotherapy, or both. For this reason, some experts and patient initiatives advocate screening; that is, the systematic examination of a social group or population for the presence of anxiety disorders, even in people who do not seek help for corresponding symptoms. Other experts argue against screening as there is no evidence that such screening has more benefit than harm (e.g. through misdiagnosis and side effects of unnecessarily prescribed medication).
What are the GAD-7 and GAD-2 questionnaires?
The GAD-7 (Generalized Anxiety Disorder 7-item scale) and the GAD-2 (the first two items of the GAD-7 scale) are user-friendly, self-completed questionnaires designed for laypeople. They help provide information on whether an individual may be suffering from an anxiety disorder. People completing the questionnaire indicate on a scale from 0 (never present) to 3 (present daily) how often they experience important anxiety symptoms. Responses are added up to obtain a total score ranging from 0 to 21. The GAD-7 is deemed 'test positive' when the total score reaches 10 or above, suggesting a potential anxiety disorder. A score of 3 or higher on the GAD-2 indicates the same. If the total score is below 10 for GAD-7 or below 3 for GAD-2, the result is considered 'test negative'.
What did we want to find out?
We aimed to find out how accurately the GAD-7 and GAD-2 scales can tell whether a person has an anxiety disorder or not.
What did we do?
We searched for studies that investigated the accuracy of the GAD-7 or GAD-2 scales (or both) by comparing them with a full diagnostic interview conducted by a healthcare professional, and we combined the results from these studies.
What did we find?
Our review includes results from 48 studies with 19,228 people from 27 different countries, evaluating the GAD-7 and the GAD-2 questionnaire in 24 different languages. Seven studies were undertaken in non-clinical settings (e.g. general population), nine in clinical settings recruiting participants with different conditions (e.g. people who sought primary care), and 32 in clinical settings with participants having specific conditions (e.g. people with epilepsy). Many of these studies investigated the accuracy of the questionnaires for one specific type of anxiety disorder (generalised anxiety disorder), others for any type of anxiety disorder, or for both.
Overall, the GAD-7 and GAD-2 questionnaires were acceptable or good at determining whether a person was suffering from an anxiety disorder.
To illustrate, if the GAD-7 questionnaire was used by a group of 1000 people, 120 (12%) of whom actually have a generalised anxiety disorder, one would expect the following results: an estimated 156 people (16%) would be classified 'test positive' by the GAD-7. However, of these, only about half (77 people or 8%) actually would have generalised anxiety disorder, while the other half (79 people or 8%) would be "false positives." Of the 844 (84%) people who tested negative, the vast majority (801 people or 80%) would be correctly classified as not suffering from generalised anxiety disorder, but 43 people (4%) with generalised anxiety disorder would be "false negatives".
The shorter GAD-2 questionnaire seems as accurate as the longer GAD-7 scale in detecting anxiety disorders. Both questionnaires seem slightly better at detecting generalised anxiety disorder than detecting any anxiety disorder.
What are the limitations of the evidence?
The studies varied in several ways, generally demonstrating poor methodological quality. The variations included differences in the population to whom the questionnaires were administered, the language of the questionnaire, methodological quality, and the method used for making the final diagnosis. These variations might explain why the accuracy of the GAD-7 and GAD-2 significantly differs across individual studies. This means that the diagnostic accuracy of these questionnaires could be better or worse in specific situations than in the summary illustration we provided above.
How current is the evidence?
The evidence is current to January 2024.
The GAD-7 and the GAD-2 scales have been tested in numerous languages and different populations. Overall, the GAD-7 and the GAD-2 seem to have acceptable or good diagnostic accuracy for both generalised anxiety disorder and any anxiety disorder. The GAD-2 scale seems to have similar diagnostic accuracy as the GAD-7 scale. However, due to the diversity of the included studies and the heterogeneity of our findings, our summary estimates of sensitivity and specificity should be interpreted as rough averages. The performance of GAD-7 and GAD-2 may deviate substantially from these values in specific situations.
Anxiety disorders often remain undetected and can cause substantial burden. Amongst the many anxiety screening tools, the 7-item Generalized Anxiety Disorder (GAD-7) scale and its short version, the 2-item Generalized Anxiety Disorder (GAD-2) scale, are the most frequently used instruments.
Primary: to determine the diagnostic accuracy of GAD-7 and GAD-2 to detect generalised anxiety disorder (GAD) and any anxiety disorder (AAD) in adults.
Secondary: to investigate whether their diagnostic accuracy varies by setting, anxiety disorder prevalence, reference standard, and risk of bias; to compare the diagnostic accuracy of GAD-7 and GAD-2; to investigate how diagnostic performance changes with the test threshold.
We searched MEDLINE, Embase, PubMed-not-MEDLINE subset, and PsycINFO from 1990 to 18 January 2024. We checked reference lists of included studies and review articles.
We included cross-sectional studies conducted in adults, containing diagnostic accuracy information on GAD-7 and/or GAD-2 questionnaires for the target conditions generalised anxiety disorder and/or any anxiety disorder, and allowing the generation of 2x2 tables. The target conditions must have been diagnosed using a structured or semi-structured clinical interview. We excluded case-control studies and studies in which the time elapsed between the index tests and reference standards exceeded four weeks. We excluded studies involving people (1) seeking help in mental health settings or (2) recruited specifically due to mental health symptoms in other settings.
At least two review authors independently decided on study eligibility, extracted data, and assessed the risk of bias and applicability of included studies. For each questionnaire and each target condition, we present sensitivity and specificity with 95% confidence intervals (95% CI) in forest plots. We used the bivariate model to obtain summary estimates based on cut-offs closest to the recommended values (i.e. within a core range). In secondary analyses, we used the bivariate model and the multiple thresholds model to obtain summary estimates for all available cut-off points. Using the multiple thresholds model, we also calculated the area under the receiver operating characteristic curve to obtain a general indicator of the diagnostic accuracy of GAD-7 and GAD-2.
We included 48 studies with 19,228 participants from 27 different countries, evaluating the GAD-7 and the GAD-2 in 24 different languages. Seven studies were performed in non-clinical settings, nine in clinical settings recruiting participants across conditions, and 32 in clinical settings with participants having specific conditions. Even after categorisation into three settings, the study populations were substantially different. The most frequently studied populations were people: with epilepsy (nine studies); with cancer (five studies); with cardiovascular disease (five studies); and in primary care regardless of their condition (five studies). We considered the risk of bias low in eight studies, and we had low concerns about the applicability of findings in three studies.
Thirty-five studies contributed to the primary analyses of GAD-7 for detecting generalised anxiety disorder (median prevalence 12%); 22 studies to analyses of GAD-7 for any anxiety disorder (median prevalence 19%); 24 studies to analyses of GAD-2 for generalised anxiety disorder (median prevalence 9%); and 19 studies to analyses of GAD-2 for any anxiety disorder (median prevalence 19%).
At the recommended cut-off of 10 or higher (or the closest available cut-off), the GAD-7 questionnaire yielded a summary sensitivity of 0.64 (95% CI 0.56 to 0.72) and a summary specificity of 0.91 (95% CI 0.87 to 0.93) in detecting generalised anxiety disorder. For detecting any anxiety disorder, summary sensitivity was 0.48 (95% CI 0.40 to 0.57) and summary specificity 0.91 (95% CI 0.89 to 0.93).
At the recommended cut-off of 3 or higher (or the closest available cut-off), the GAD-2 yielded a summary sensitivity of 0.68 (95% CI 0.59 to 0.75) and a summary specificity of 0.86 (95% CI 0.82 to 0.89) for detecting generalised anxiety disorder. For detecting any anxiety disorder, the summary sensitivity was 0.53 (95% CI 0.44 to 0.62) and the summary specificity was 0.89 (95% CI 0.86 to 0.91).
The 95% prediction region of GAD-7 for detecting generalised anxiety disorder was larger (indicating pronounced statistical heterogeneity) than for the three other analyses. Specificity varied by setting in the analysis of GAD-7 and GAD-2 for detecting any anxiety disorder, and by reference standard in the analysis of GAD-2 for detecting generalised anxiety disorder. Sensitivity varied with prevalence in the analysis of GAD-7 for generalised anxiety disorder. Other investigations of potential sources of heterogeneity did not show statistically significant associations with test accuracy. In all analyses, sensitivity tended to be higher and specificity lower in participants with specific conditions compared to the other two settings. Overall, the heterogeneity in the subgroup analyses remained high.
The area under the receiver operating characteristic curve in the multiple thresholds model was 0.86 (95% CI 0.84 to 0.88) for the GAD-7 scale in detecting generalised anxiety disorder, and 0.80 (95% CI 0.78 to 0.82) in detecting any anxiety disorders. For the GAD-2 scale, the value was 0.82 (95% CI 0.81 to 0.86) for detecting generalised anxiety disorder, and 0.77 (95% CI 0.76 to 0.82) for detecting any anxiety disorders. Comparative bivariate analyses revealed no statistically significant differences between the diagnostic test accuracy of GAD-7 and GAD-2.