Health-related quality of life may be assessed directly, such as with the standard gamble, time trade-off, visual analog scale, or indirectly with the person reporting their own health status, which is then scored using community preference weights (e.g., EuroQol, Health Utilities Index, self-administered Quality of Well-being scale) or other scoring system (e.g., SF-36). How the direct and indirect methods compare has not been fully explored, and there may be factors that systematically affect the assessment of quality of life and the relationship between direct and indirect measures. One such factor is the duration of the illness/symptom. There is some evidence that a person adapts to a chronic condition, with a decrease in the condition's disutility over time. There is also a question whether patients and non-patients weigh the same condition equally. This project evaluates duration as a modifying factor related to quality of life and utility assessment. Specifically, the aims of this project are to evaluate (1) how a condition's duration affects a patient's mean daily preference weight for that condition, (2) how a condition's duration affects a control's mean daily preference weight for that condition and to determine whether there are differences in the assessments of patients and controls, (3) whether the duration of a patient's illness affects that person's mean daily preference weight for that condition, and (4) whether health-related quality of life of patients as assessed using four generic measures varies systematically with the vignette-described duration of the illness. This exploratory project starts with focus groups to learn more how symptom duration is a modifying factor for health-related quality of life. Vignettes that highlight these factors will then be constructed, in the second part these vignettes will be shown to patients and controls representing diverse backgrounds. The patients and controls will be asked to rate the health states using the standard gamble, time trade-off, visual analog scale; patients will also be asked to rate health states using the EQ-5D, HUI, QWB-SA, and SF-36. The results will provide insight into the psychology of quality of life assessment, allowing for the development of better models of health-related quality of life and, potentially, better quality of life instruments.
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