A comparison of the Work and Social Adjustment Scale (WSAS) across different patient populations using Rasch analysis and exploratory factor analysis

- Compared item hierarchy of the Work and Social Adjustment Scale in patients with HIV, breast cancer, inflammatory conditions.
- Exploratory factor analysis and principle component analysis of the WSAS showed a good fit as a unidimensional scale.
- Differential item functioning was seen by diagnosis and by sex for items 1 and 5 of the WSAS.

IntroductionThe Work and Social Adjustment Scale (WSAS) is designed to measure patients' perceived functional impairment associated with a health problem. There is a paucity of studies that explore the stability of the item hierarchy in the WSAS across different disease populations. This study investigated the unidimensional structure of the WSAS across different disease populations.MethodsSecondary data analysis was conducted on pooled patient data (HIV, breast cancer, and inflammatory conditions) to create a new dataset (n = 554). The data were analysed using Rasch analysis and exploratory factor analysis.ResultsExploratory factor analysis and principle component analysis of the WSAS showed a good fit as a unidimensional scale, person and item separation indices were > 2 suggesting that the WSAS is sensitive enough to distinguish between participants of varying levels of ability. Some differential item functioning was seen by diagnosis and by sex for items 1 and 5 of the WSAS.ConclusionsOverall, a one dimensional structure was identified for the WSAS. However, a small number of differential item functioning (DIF) was identified, suggesting that scores from the WSAS cannot be compared across groups.