Distinguishing between quality of life and health status in quality of life research: A meta-analysis

Despite the increasing acceptance of quality of life (QOL) as a critical en dpoint in medical research, there is little consensus regarding the definit ion of this construct or how it differs from perceived health status. The o bjective of this analysis was to understand how patients make determination s of QOL and whether QOL can be differentiated from health status. We condu cted a meta-analysis of the relationships among two constructs (QOL and per ceived health status) and three functioning domains (mental, physical, and social functioning) in 12 chronic disease studies. Instruments used in thes e studies included the RAND-36, MOS SF-20, EORTC QLQ-30, MILQ and MQOL-HIV. A single, synthesized correlation matrix combining the data from all 12 st udies was estimated by generalized least squares. The synthesized matrix wa s then used to estimate structural equation models. The meta-analysis resul ts indicate that, from the perspective of patients, QOL and health status a re distinct constructs. When rating QOL, patients give greater emphasis to mental health than to physical functioning. This pattern is reversed for ap praisals of health status, for which physical functioning is more important than mental health. Social functioning did not have a major impact on eith er construct. We conclude that quality of life and health status are distin ct constructs, and that the two terms should not be used interchangeably. M any prominent health status instruments, including utility-based questionna ires and health perception indexes, may be inappropriate for measuring QOL. Evaluations of the effectiveness of medical treatment may differ depending on whether QOL or health status is the study outcome.