Objective: To systematically review the accuracy of the GAD-7 and GAD-2 questionnaires for identifying anxiety disorders.
Methods: A systematic review of the literature was conducted to identify studies that validated the GAD-7 or GAD-2 against a recognized gold standard diagnosis. Pooled estimates of diagnostic test accuracy were produced using random-effects bivariate metaanalysis. Heterogeneity was explored using the I(2) statistic.
Results: A total of 12 samples were identified involving 5223 participants; 11 samples provided data on the accuracy of the GAD-7 for identifying generalized anxiety disorder (GAD). Pooled sensitivity and specificity values appeared acceptable at a cutoff point of 8 [sensitivity: 0.83 (95% CI 0.71-0.91), specificity: 0.84 (95% CI 0.70-0.92)] although cutoff scores 7-10 also had similar pooled estimates of sensitivity/specificity. Six samples provided data on the accuracy of the GAD-2 for identifying GAD. Pooled sensitivity and specificity values appeared acceptable at a cutoff of 3 [sensitivity: 0.76 (95% CI 0.55-0.89), specificity: 0.81 (95% CI 0.60-0.92)]. Four studies looked at the accuracy of the questionnaires for identifying any anxiety disorder.
Conclusions: The GAD-7 had acceptable properties for identifying GAD at cutoff scores 7-10. The GAD-2 had acceptable properties for identifying GAD at a cutoff score of 3. Further validation studies are needed.
Keywords: Anxiety; Diagnostic test accuracy; Generalised anxiety disorder; Sensitivity and specificity; Systematic review.
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