Variability among methods to assess patients' well-being and consequent effect on a cost-effectiveness analysis

Cost-effectiveness analysis is emerging as an approach for determining the relative value of health care programs, technologic innovations, and clinical decisions. Increasingly, patients' stated values for quality of life are applied as adjustment in these analyses; the results may vary depending on how individuals assess their well-being. We interviewed 58 patients with chronic renal failure to determine the level of agreement among six methods for assessing well-being, and to determine the effects of variation in assessed well-being on the results of a cost-effectiveness analysis of in-center hemodialysis. Patients reported well-being using the Sickness Impact Profile, Campbell Index of Well-being, Kaplan-Bush Index of Well-being, categorical scaling, standard gamble, and time trade-off. We found that patient well-being was substantially higher as evaluated by the Sickness Impact Profile compared to the other five methods. The Sickness Impact Profile and the Kaplan-Bush Index of Well-being provided much narrower distributions of assessed values relative to other measures. Correlations among assessment methods were poor (Spearman rank-correlation coefficients range: 0.094-0.519). Discrepancies among indices were particularly vivid when we evaluated data at the individual level; many patients reported a high level of well-being according to one index and a low level of well-being according to a different index. The cost effectiveness of in-center hemodialysis varied from $34,893 to $45,254 per quality-adjusted life-year saved according to the Sickness Impact Profile and standard-gamble technique respectively. The substantial variability in patients' stated quality of life may preclude the use of a single method to analyze the cost effectiveness of a health program.