Objectives To investigate the factor structure and internal consistency of the Hospital Anxiety and Depression Scale (HADS) in individuals with Chronic Fatigue Syndrome (CFS) using an Internet administered version of the instrument.
Design Between subjects.
Method Confirmatory factor analysis (CFA) and internal consistency analysis of the HADS was used to determine the psychometric characteristics of the instrument in individuals with CFS and a control group with data captured via an Internet data collection protocol.
Results CFA revealed that a 3-factor solution offered the most parsimonious account of the data. Internal consistency estimations of the anxiety and depression subscales were found to be acceptable for both groups. The CFS group was found to have significantly higher HADS-assessed anxiety and depression scores compared with controls, however, there was also evidence found that Internet administration of the instrument may inflate HADS subscale scores as an artifact of testing medium.
Conclusions The HADS is suitable for use for screening individuals with CFS in terms of the factor structure of the instrument, however, clinicians should be aware that this instrument assesses 3 domains of affective disturbance rather than 2 as is interpreted within the current HADS anxiety and depression subscale scoring system. Researchers need also be aware that Internet administration of negative affective state measures such as the HADS is likely to inflate scores and need to ensure that comparisons between clinical groups are made with control group data gathered using the same collection methodology.