Bifactor analysis of the Hospital Anxiety and Depression Scale (HADS) for individuals with traumatic brain injury

Abstract

Abstract Anxiety and depression are two of the most common forms of psychopathology experienced after traumatic brain injury (TBI), yet there is a scarcity of studies validating measures of anxiety and depression for use with this population. Using symmetrical bifactor modeling, we evaluated whether the Hospital Anxiety and Depression Scale (HADS) reliably differentiated anxiety and depression in 874 adults with moderate-severe TBI. There was a dominant general distress factor accounting for 84% of the systematic variance in the HADS total score. The specific anxiety and depression factors accounted for little residual variance in their respective subscale scores (12% and 20%, respectively), and overall, minimal bias was found in using the HADS as a unidimensional measure. Further, in a subsample (n=184), the HADS subscales did not clearly discriminate between formal anxiety and depressive disorders diagnosed via semi-structured clinical interview. Results were consistent when accounting for degree of disability, non-English speaking background, and time post-injury. In conclusion, variance in HADS scores after TBI predominately reflects a single underlying latent variable. Clinicians and researchers working with individuals with TBI should exercise caution in interpreting the individual HADS subscales, instead considering using the total score as a more valid measure of general distress.