The GAD-7 scale is a brief self-report questionnaire previously shown to provide valid assessments of generalised anxiety symptoms in various clinical settings and among the general population [25]. This instrument has been used as both a screening tool and severity measure with patients with GAD [25, 26]. The scale comprises seven items [25]:

Feeling nervous, anxious or on edge

Not being able to stop or control worrying

Worrying too much about different things

Having trouble relaxing

Being so restless that it is hard to sit still

Becoming easily annoyed or irritable

Feeling afraid as if something terrible might happen

The items correspond to symptoms based on the criteria for GAD. The GAD-7’s recall period is the two previous weeks, and the questions are answered on a 4-point Likert scale. The GAD-7 index is calculated by assigning scores of 0, 1, 2 and 3 to the response categories of ‘not at all’, ‘several days’, ‘more than half the days’ and ‘nearly every day’, respectively, and adding together the scores for the 7 questions. Scores of 5, 10 and 15 are taken as the cut-off points for mild, moderate and severe anxiety, respectively. GAD-7 has been found in recent years to be a reliable, valid questionnaire in different languages, including Portuguese [27]. The present study used the Portuguese version of GAD-7 [27].