Are underlying constructs measured by different quality of life instruments really that different? Using factor and latent path analysis to compare latent constructs measured by six instruments

Introduction: It is important that quality of life (QoL) instruments measure the underlying QoL constructs that are important in their target population. A plethora of QoL instruments designed to measure different QoL constructs exist. However, it is not always clear whether the constructs purportedly measured by these instruments are really that different especially when similar language is used in describing the instruments. This study compares the constructs measured by six instruments focussing on health-related QoL (EuroQoL 5 Dimensions 5 Level (EQ-5D-5L)), older-people-specific QoL (Older People’s Quality of Life brief questionnaire (OPQoL-brief)), social-care-related QoL (Adult Social Care Outcomes Toolkit (ASCOT)), capabilities (ICEpop CAPability measure for Older people (ICECAP-O), mastery (Pearlin Mastery Scale) and self-esteem (Rosenberg Self-Esteem Scale).