A structural equation modelling approach to explore the determinants of quality of life in schizophrenia

Abstract

Objective: This study aimed to analyse the relationships among psychotic symptoms, depression, neurocognition and functioning as determinants of quality of life (QoL) in patients with schizophrenia.

Methods: In this cross-sectional study, we evaluated QoL with the Schizophrenia Quality of Life 18-item scale (S-QoL 18), neurocognition with multiple tests exploring memory, attention and executive functions, the severity of psychotic symptoms with the Positive and Negative Syndrome Scale (PANSS), depression with the Calgary Depression Scale for Schizophrenia (CDSS) and functioning using the Functional Remission Of General Schizophrenia (FROGS) scale. We used Structural Equation Modelling (SEM) to describe the relationships among the severity of psychotic symptoms, depression, neurocognition, functioning and QoL.

Results: Two hundred and seventy-one outpatients with schizophrenia participated in our study. SEM showed good fit with χ(2)/df=1.97, root mean square error of approximation=0.06, comparative fit index=0.93 and standardized root mean square residuals=0.05. This model revealed that depression was the most important feature associated with QoL, mainly for the self-esteem, autonomy and resilience dimensions (direct path coefficient=-0.46). The direct path between functioning and QoL was also significant (path coefficient=0.26). The severity of psychotic symptoms and neurocognitive impairment were weakly and indirectly associated with QoL via functioning (path coefficients=-0.18 and 0.04, respectively).

Conclusions: This study contributes to a better understanding of the determinants of QoL in schizophrenia. Our findings should be considered in developing effective strategies for improving QoL among this population.

Keywords: Depression; Functioning; Neurocognition; Psychotic symptoms; Quality of life; Schizophrenia; Structural equation modelling.