Abstract
Background: The EQ-5D is a generic health-related quality of life questionnaire often used to calculate QALYs in economic evaluations. Adding a respiratory dimension to the current 5 dimensions could improve its responsiveness to changes in patients with respiratory problems. We aimed to evaluate the impact of adding a respiratory dimension (i.e. a bolt-on) on EQ-5D utility values.
Methods: Regression- and principal component analyses identified two respiratory bolt-on candidate items: 1) breathing problems and 2) impact of shortness of breath on physical activities (levels: no/slight/moderate/severe/extreme problems or unable to do). Valuation interviews (>200) for each candidate bolt-on were performed with a representative sample from the Dutch general public using the composite time-trade off (TTO) method and a discrete choice experiment (DCE).
Results: Observed mean TTO values for health states with a level 4 or 5 for the respiratory dimension were significantly lower compared to the same health states observed in the Dutch EQ-5D-5L study without respiratory dimension. Results of regression models showed that for the bolt-on candidate “impact of shortness of breath on physical activities” utility decrements were significant for level 3 (-0.055), level 4 (-0.087) and level 5 (-0.135). For the “breathing problems” bolt-on, the coefficients for the same levels were lower (-0.086, -0.219 and -0.327, respectively).
Conclusion: Addition of both respiratory bolt-ons to the EQ-5D-5L had a significant effect on the valuation of health states but the bolt-on dimension on “breathing problems” showed the greatest impact and therefore seems the most appropriate respiratory bolt-on dimension.
- Copyright ©the authors 2016
