The Hospital Anxiety and Depression Scale (HADS) is commonly used clinically and scientifically among surrogate decision makers for critically ill patients. The validity of the HADS has been scrutinized, but its use among surrogate decision makers has not been examined.
To examine the structural validity of the HADS.
This study was a secondary analysis of data obtained from a 3-arm randomized controlled trial of a decision support intervention. Participants were recruited from 6 intensive care units at a tertiary medical center in Northeast Ohio. Participants were adult surrogate decision makers for critically ill, cognitively impaired adults who were not expected to be discharged from the intensive care unit within the subsequent 48 hours. The fit of 2-factor, 3-factor, and bifactor structures of the HADS was tested with confirmatory factor analysis.
The bifactor structure, possessing a general psychological distress factor and anxiety and depression group factors, showed a superior fit and met a priori thresholds for acceptable model fit. The general psychological distress factor accounted for more than 75% of the common variance in the HADS items.
Confirmatory factor analysis provided evidence supporting a bifactor structure of the HADS. In this sample, the instrument validly measures psychological distress rather than distinct symptoms of anxiety and depression. Replication of these results is encouraged, and use of alternative measures is recommended when measuring distinct symptoms of anxiety and depression among surrogate decision makers for critically ill patients.