Brief case finding tools for anxiety disorders: validation of GAD-7 and GAD-2 in addictions treatment

Anxiety disorders are the most common mental health problems and often co-exist with substance use. Little evidence exists to support the use of brief screening tools for anxiety disorders in routine addictions treatment. This is the first study to test the validity and reliability of GAD-7 and GAD-2 in an outpatient drugs treatment population.

A sample of 103 patients completed brief screening questionnaires and took part in structured diagnostic assessments using CIS-R. A subgroup of 60 patients completed retests after 4 weeks. The results of brief questionnaires were compared to those of gold-standard diagnostic interviews using Receiver Operating Characteristic (ROC) curves. Psychometric properties were also calculated to evaluate the validity and reliability of self-completed questionnaires.

A GAD-7 score ≥ 9 had a sensitivity of 80% and specificity of 86% for any anxiety disorder, also displaying adequate temporal stability at repeated measurements (intra-class correlation=0.85) and high internal consistency (Cronbach's alpha=0.91). A GAD-2 score ≥ 2 had 94% sensitivity and 53% specificity, with adequate internal consistency (0.82).

GAD-7 adequately detected the presence of an anxiety disorder in drug and alcohol users; although this study was limited by sample size to determine its reliability for specific diagnoses. Results in this small sample suggest that GAD-7 may be a useful screening tool in addiction services, although replication in a larger sample is warranted.