EQ-5D health utility values in the treatment Of seasonal grass pollen induced rhinoconjunctivitis

Rationale: Standard clinical efficacy endpoints in allergen immunotherapy trials include the daily Rhinoconjunctivitis Symptom Score (RSS) and daily Rhinoconjunctivitis Medication Score (RMS). However, measurement of subjects' QoL in terms of health utility is also necessary to characterise changes in health status. In this study, we aimed to determine a relationship between standard efficacy endpoints and the health utility. Methods: Data from a 5-year DBPC phase III trial (GT-08, ALK, Denmark) in subjects with grass pollen induced rhinoconjunctivitis were analysed. During each pollen season, subjects recorded daily their RSS and RMS and weekly the EQ-5D index. A two-stage model was constructed: 1) binomial modelling of subjects with “perfect health” (EQ-5D utility=1) and 2) Gaussian modelling of EQ-5D utilities< 1. The utility during each grass pollen season was calculated as area under the curve. Results: A total of 16,690 weekly and 137,792 daily EQ-5D observations were recorded over the trial period. The binomial model showed the daily RSS and RMS to be the two most important predictors of “perfect health” (RSS: OR=0.729; p< 0.001; RMS: OR=0.841; p< 0.001). The Gaussian model of subjects with “imperfect health” confirmed this correlation. Based on relationship the average annual utility was estimated to 2.2 QALD. Conclusions: In a clinical trial including subjects with grass pollen induced rhinoconjunctivitis, the daily RSS and RMS were found to be suitable predictors of the EQ-5D health utility. The findings confirm the beneficial impact of the SQ-standardised Timothy grass allergy immunotherapy tablet (75,000 SQ-T/2,800 BAU, ALK) on health utilities with a clinical relevant QALY gain