GAD-7 calculator (anxiety severity score)

How this GAD-7 calculator works

This GAD-7 calculator adds the seven answers of the Generalized Anxiety Disorder 7-item scale, each scored from 0 to 3, to give a total from 0 to 21. Spitzer, Kroenke, Williams and Löwe published the GAD-7 in the Archives of Internal Medicine in 2006 as a brief self-report scale to identify probable generalized anxiety disorder and grade its severity. They began with 13 candidate items, nine reflecting the DSM-IV symptom criteria and four taken from existing anxiety scales, and kept the 7 that correlated best with the 13-item total. Each item asks how often, over the last 2 weeks, a problem has bothered the patient: not at all (0), several days (1), more than half the days (2) or nearly every day (3). The study enrolled 2,740 adults in 15 US primary care clinics, and 965 had a telephone interview with a mental health professional within 1 week. Internal consistency was excellent (Cronbach's alpha 0.92), and test-retest reliability gave an intraclass correlation of 0.83.

According to the paper, the first three items capture the two core DSM-IV criteria for generalized anxiety disorder (A and B). The paper also found good agreement between the self-report version and a version read out by an interviewer, with an intraclass correlation of 0.83.

Worked example, checked by hand: a patient answers 2, 2, 1, 2, 1, 2 and 1 to items 1 to 7. Four items at 2 give 8 points and three items at 1 give 3, for a total of 11, in the moderate band and above the cut-off of 10. Items 1 and 2 add to 4, so the GAD-2 is also positive. These are the answers loaded in the calculator above. What each range means is set out in GAD-7 score interpretation, and the GAD-7 is set beside the depression questionnaire in PHQ-9 vs GAD-7.

GAD-7 severity bands and the cut-off of 10

The GAD-7 severity bands come from Spitzer 2006, which proposed that cut points of 5, 10 and 15 might be read as mild, moderate and severe levels of anxiety; the paper's tables label 0 to 4 as minimal, and the PHQ and GAD-7 instruction manual uses the same cut points. A score of 10 or more is the paper's cut point for identifying probable generalized anxiety disorder. Against the mental health professional interview it had a sensitivity of 89% and a specificity of 82%: most patients with generalized anxiety disorder scored 10 or more, and most without it scored under 10. In the same primary care sample, 23% of patients scored 10 or more, so a positive screen calls for a clinical assessment rather than a label. Raising the cut point to 15 maximized specificity, at 95%, but caught only 48% of cases. Rising GAD-7 scores were strongly linked with poorer function on all six SF-20 health survey scales and with more disability days.

How each cut-off performed for generalized anxiety disorder in the 965 interviewed patients (Spitzer 2006):

The GAD-2: the first two GAD-7 items

The GAD-2 is the first two items of the GAD-7, feeling nervous, anxious or on edge, and not being able to stop or control worrying, each scored 0 to 3 for a total from 0 to 6. The PHQ and GAD-7 instruction manual describes these as the two core DSM-IV items for generalized anxiety disorder and recommends a cut point of 3 or more when the GAD-2 is used as a screener; a positive GAD-2 should prompt the full GAD-7 and a clinical interview to find out whether a mental disorder is present. This calculator shows the GAD-2 subscore under the total, so a GAD-7 completed in full also shows what the two-item screen would have found. In the 965 interviewed primary care patients analysed by Kroenke and colleagues in 2007, both the GAD-7 and the GAD-2 performed well as screens for generalized anxiety disorder, panic disorder, social anxiety disorder and post-traumatic stress disorder, with areas under the ROC curve from 0.80 to 0.91.

A later meta-analysis by Plummer and colleagues (General Hospital Psychiatry, 2016) pooled 12 samples and 5,223 participants. For generalized anxiety disorder, the GAD-2 at 3 or more had a pooled sensitivity of 76% and specificity of 81% across six samples, and the GAD-7 had acceptable accuracy at cut-offs from 7 to 10, with 83% sensitivity and 84% specificity at a cut-off of 8.

When the GAD-7 is less reliable

The GAD-7 is a self-report screening and severity scale, so its total depends on how the patient reads and answers seven items about the last 2 weeks, and it does not replace a diagnostic interview. How much a positive score means depends on how common the disorder is. In Spitzer 2006, a score of 10 or more had a positive predictive value of only 29% and a negative predictive value of 99%: a score under 10 made generalized anxiety disorder unlikely, while most positive screens turned out not to be that disorder. Kroenke and colleagues found generalized anxiety disorder in 7.6% of the interviewed patients, yet 19.5% had at least one anxiety disorder, so a high GAD-7 can also reflect panic, social anxiety or post-traumatic stress disorder. The validation sample came from US primary care, with a mean age of 47 years, 65% women and 80% white non-Hispanic patients, and the instruction manual notes that few translations have been checked against an independent structured psychiatric interview.

Anxiety and depression often occur together. Spitzer 2006 found that factor analysis confirmed them as distinct dimensions with separate effects on function, so a GAD-7 does not stand in for a depression screen, and it has no item on self-harm. The PHQ-9 calculator scores depressive symptoms and flags its self-harm item. A total also hides which symptoms drive it, so read the individual answers as well as the sum.