SF-6D utility values for better- and worse-seeing eye for health states based on the Snellen equivalent in patients with Age-Related Macular Degeneration

Objective: Economic evaluations in wet age-related macular degeneration (ARMD) tend to overestimate the effect of interventions, in terms of quality of life (QOL), as the interaction between the worse seeing eye (WSE) and the better seeing eye (BSE) is not incorporated. Some ad hoc modelling approaches are published to incorporate this interaction.  In this investigation we set out to provide SF-6D utility estimates for health states of ARMD, that incorporated this interaction based on data of a clinical trial.

Methods: SF-6D data of 191 ARMD patients (>65 years) were used to fill health states defined by the combination of WSE and BSE using Snellen equivalents; no visual loss (≥20/40), mild-moderate (<20/40 - >20/200) and severe (≤20/200).

Results: We found a consistent linear relation between health states and SF-6D and found an interaction between changes in the WSE and BSE. In this elderly population, co-morbidity did produce considerable background noise.

Conclusion: We provide utility values for economic modeling in ARMD when direct utility measures are lacking. Besides, the results presented here provide a solution to overcome overestimation of the effect of interventions in ARMD and will result in more valid and more conservative estimates of the effects.