Application of a Mapping Function to Estimate Utilities for Ragweed Allergy Immunotherapy Trials

Abstract

Background: Ragweed pollen sensitivity is a common cause of allergic rhinitis (AR) worldwide. AR symptoms include itchy and runny eyes, sneezing, blocked nose, impaired sleep and social and emotional problems, which can have a significant impact on quality of life. Objective: The objective of this analysis was to estimate utilities for two pooled standardised quality (SQ) ragweed sublingual immunotherapy (SLIT) tablet trials by applying a previously developed mapping algorithm. This study validated the algorithm and extended its application to ragweed seasonal allergy trials. The mapping algorithm relates disease-specific quality-of-life scores to preference-based utilities that may be used to calculate quality-adjusted life-years (QALYs) in cost-effectiveness studies. Methods: A mapping algorithm based on a grass pollen allergy immunotherapy trial, GT-08 (EudraCT no. 2004-000083-27) was applied to pooled data from two ragweed pollen immunotherapy trials, P05233 (EudraCT 2008-003863-38) and P05234 (EudraCT 2008-003864-20) to generate EuroQoL 5-Dimensions, 3-Levels (EQ-5D-3L) utilities from Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) data. Results: The mean utility difference between the SQ ragweed SLIT tablet and placebo was 0.025 [95% confidence interval (CI) 0.011–0.038]. The SQ ragweed SLIT tablet showed an incremental quality-adjusted life-days (QALDs) benefit of 1.900 (95% CI 0.835–2.916) over 75 days. Conclusions: Application of a previously developed mapping function allowed for the calculation of QALDs associated with the SQ ragweed SLIT tablet. The results showed a QALD benefit of the SQ ragweed SLIT tablet in P05233 and P05234 trials in the treatment of ragweed pollen-induced AR.