Anxiety Treatment Improves Physical Functioning with Oblique Scoring of the SF-12 Short Form Health Survey

Published In: General Hospital Psychiatry, v. 35, no. 3, May-June 2013, p. 291-296

Posted on RAND.org on January 01, 2013

by Andrea N. Niles, Cathy D. Sherbourne, Peter Roy-Byrne, Murray Stein, Greer Sullivan, Alexander Bystritsky, Michelle G. Craske

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OBJECTIVE: No studies have found a positive effect of anxiety treatment on physical functioning, but recent investigations of the 12-item Short Form Health Questionnaire (SF-12), which is frequently used to assess physical functioning, have suggested that orthogonal scoring of the summary measure may distort representations of physical health. The current study reanalyzes whether anxiety treatment improves physical functioning using oblique scoring in the Coordinated Anxiety Learning and Management (CALM) randomized clinical trial for the treatment of anxiety disorders. Replication was tested in reanalysis of data from the earlier Collaborative Care for Anxiety and Panic (CCAP) randomized clinical trial for the treatment of panic disorder. METHOD: The CALM study included 1004 primary care patients with panic, social anxiety, generalized anxiety or posttraumatic stress disorders. Patients received usual care (UC) or an evidence-based intervention (cognitive behavioral therapy, psychotropic medication or both; ITV). Physical functioning (SF-12v2) was assessed at baseline and at 6, 12 and 18 months. Oblique and orthogonal scoring methods for the physical functioning aggregate measure from SF-12 scale items were compared. RESULTS: In CALM, physical functioning improved to a greater degree in ITV than UC for oblique but not orthogonal scoring. Findings were replicated in the CCAP data. CONCLUSIONS: Evidence-based treatment for anxiety disorders in primary care improves physical functioning when measured using oblique scoring of the SF-12. Due to this scoring issue, effects of mental health treatment on physical functioning may have been understated.

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