Patient and public preferences for health states associated with AMD

Health utility values suitable for calculating quality-adjusted life-years are increasingly used to assess the cost-effectiveness of treatments for age-related macular degeneration (AMD). In the United States, health utilities are usually derived from the patients' own valuation or modeled using visual acuity as a surrogate outcome. In the United Kingdom and throughout Europe, health utilities are derived from public valuations. Our aim was to test if utility values for health states associated with AMD elicited directly from patients were different from those calculated from public tariffs for health-related quality of life (HRQoL) questionnaires.

Generic preference-based HRQoL questionnaires (EQ-5D and SF-6D) and the time trade-off (TTO) and visual analog scale (VAS) valuation techniques were administered to a sample of UK patients with AMD (N = 60). Health utilities were calculated using standard general population tariffs for the patient EQ-5D and SF-6D health states and directly from patient TTO and VAS scores.

Mean utilities derived from the public tariffs were significantly higher than from patients' valuation (mean [±SD], 0.613 (±0.275) for the EQ-5D and 0.628 (±0.114) for the SF-6D compared with 0.481 [±0.411] for the TTO and 56.7 [±21.8] for the VAS score; p < 0.001). The EQ-5D was not significantly different from the SF-6D (p > 0.6). Visual acuity in the better seeing eye was not associated with any utility measure (all r < 0.08; p > 0.2).

Patient and public preferences for health states associated with AMD are different, with patients valuing their health state more severely than the public tariffs of commonly used HRQoL questionnaires. Visual acuity did not predict health utility using any measure, and therefore, care should be taken when using visual acuity as a surrogate measure for utility in health economic analyses.