Paediatric quality of life instruments: a review of the impact of the conceptual framework on outcomes.

With an increasing number of paediatric quality of life (QOL) instruments being developed, it is becoming difficult for researchers and clinicians to select the most appropriate instrument. Reviews of QOL instruments tend to report only basic properties of the instruments such as domains and psychometric properties. This paper seeks to appraise critically the conceptual underpinnings of paediatric QOL instruments. A systematic review was conducted to identify QOL instruments for children aged 0 to 12 years, and to examine and compare their conceptual frameworks, definitions employed, and structure. Both generic and condition-specific measures were reviewed. Fourteen generic and 25 condition-specific QOL instruments were identified. Eleven types of definition of QOL and health-related QOL and three theories of QOL were identified. QOL was measured by a variety of domains including emotional, social and physical health, and well-being. Items commonly assessed difficulties, or intensity/frequency of feelings/symptoms, in contrast to positive aspects of life and happiness. The findings highlight the diversity that is apparent in the conceptualization of paediatric QOL and draw attention to the lack of empirical evidence for many of the fundamental assumptions. The impact of the conceptual underpinnings of the instruments on the resulting QOL scores is discussed.