Psychometric properties and factorial analysis of invariance of the Satisfaction with Life Scale (SWLS) in cancer patients

Abstract

Purpose The purpose of this study was to assess the psychometric properties of the Satisfaction with Life Scale (SWLS), evaluate the measurement invariance with respect to sex, age, and tumor location, as well as analyze associations between life satisfaction and socio-demographic and clinical variables among individuals with resected, non-advanced cancer. Methods A confirmatory factor analysis was conducted to explore the dimensionality of the scale and test invariance across gender, age, and tumor localization in a prospective, multicenter cohort of 713 patients who completed the following scales: SWLS, Health-related Quality of Life Questionnaire (EORTC QLQ-C30), Brief Symptom Inventory (BSI-18). Results Confirmatory factor analysis results indicated that the SWLS is an essentially unidimensional instrument, providing accurate scores: both McDonald's omega and Cronbach's alpha estimates were 0.91. Strong measurement invariance was found to hold across gender, age, and tumor localization. Low satisfaction with life was associated with psychological symptoms (anxiety, depression, and somatization), and decreased quality of life (malfunction, symptoms, poor global QoL). Conclusion The SWLS is a reliable, valid satisfaction with life measurement among people with cancer and should be recommended as an indicator of psychological adjustment in oncological patients.