Discriminant validity of the Social Phobia and Anxiety Inventory (SPAI), the Social Phobia Scale (SPS) and the Social Interaction Anxiety Scale (SIAS)

Three measures commonly used in assessment of social phobia, the Social Phobia and Anxiety Inventory (SPAI [Turner, S. M., Beidel, D. C. & Dancu, C. V. (1996). Social phobia and anxiety inventory: manual. Toronto, Ont.: Multi-Health Systems Inc.), the Social Phobia Scale (SPS [Mattick, R. P. & Clarke, J. C. (1998). Development and validation of measures of social phobia scrutiny fear and social interaction anxiety. Behaviour Research and Therapy, 36, 455-470] and the Social Interaction Anxiety Scale (SIAS [Mattick, R. P. & Clarke, J. C. (1998). Development and validation of measures of social phobia scrutiny fear and social interaction anxiety. Behaviour Research and Therapy, 36, 455-470], were compared for their ability to discriminate between social phobia and other anxiety disorders (panic disorder with or without agoraphobia). Participants were 117 patients attending a specialized anxiety disorders unit for treatment. While all three measures were able to detect differences between social phobic patients and patients with panic disorder with or without agoraphobia, a logistic regression analysis showed that the SPAI, but not the SPS and SIAS, was a significant predictor of membership of the social phobia group. Receiver operating characteristic (ROC) analysis also showed that the SPAI was the better measure for discriminating between social phobia and panic disorder with and without agoraphobia. Analysis of the sensitivity, specificity and positive and negative predictive power of the measures at the optimum cutoff scores produced by the ROC analysis are presented.