Psychosocial functioning impairment is prevalent in first episode psychosis and chronic schizophrenia. The Quality of Life Scale (QLS) is a widely-used tool to measure psychosocial functioning; however, given the overlap between negative symptoms and functioning, along with the QLS being conceptualized initially as a measure of the deficit syndrome, it is unclear whether summing QLS items into a total score is an appropriate measure of overall psychosocial functioning. This study aimed to examine the centrality of QLS items and the appropriateness of using a QLS total score. Participants with first episode psychosis (n = 404) completed the QLS. Item centrality was assessed using a network analysis approach, while reliability and dimensionality of the QLS total score and subscales were measured using bifactor modeling and related psychometric indices. Network analysis results showed that an item relating to motivation was the most central item within the scale. Moreover, bifactor modeling results found that motivation and other items relating to negative symptoms may reflect the QLS total score more strongly than other functioning (i.e., Interpersonal, Instrumental) domains. Based on these findings, we urge researchers to use caution when using a QLS total score, as it may unequally confound functional domains and motivation. Moreover, our results continue to underscore the importance of negative symptoms, particularly motivational impairment, in psychosocial functioning. Future studies should aim to examine the centrality of other functioning measures in psychosis and schizophrenia, as our results suggest that psychosocial functioning may be greatly influenced by motivation.
Psychometric Evaluation of the Hebrew Language Version of the Satisfaction with Life Scale
