OBJECTIVES : There are currently no published health state utility values for patients with the rare disorder cerebral adrenoleukodystrophy (CALD). Given preference-based utilities are important when assessing the cost-effectiveness of treatments, we examined the feasibility of mapping patient-reported outcomes (PRO) data from CALD clinical trials onto the EuroQoL EQ-5D, an accepted health utility metric.

METHODS : PRO data generated from the Pediatric Quality of Life Inventory™ (PedsQL), a generic, non-preference-based, health-related quality of life questionnaire developed for pediatric populations, were collected in two studies of boys with CALD: ALD-102 [NCT01896102], a Phase 2/3 clinical trial evaluating elivaldogene autotemcel (eli-cel; Lenti-D) gene therapy, and ALD-103 [NCT02204904], an observational study evaluating allogeneic hematopoietic stem cell transplant (allo-HSCT). Neither study collected EQ-5D data. The mapping algorithm was based on a previously published, cross-sectional study of PedsQL and EQ-5D completed by secondary school children in England. That study estimated a regression model that included the necessary PedsQL domain scores and related coefficients to calculate EQ-5D utility scores. The transferability of the algorithm to CALD was based on the known pathophysiology of CALD as well as published literature of health utilities for similar neurologic disorders.

RESULTS : Pooled data from ALD-102 and ALD-103 (N=34) resulted in a mean (median) EQ-5D utility score of 0.88 (0.97) at baseline, indicating patients are overall healthy pre-treatment. The occurrence of major functional disabilities [MFDs] represents a rapidly declining health state for boys with CALD – the associated utility score was an estimated mean of 0.27 (range -0.38 to 0.53) (n=5). Successfully treated patients (i.e. without MFDs or retransplant) at Month 24 maintained scores similar to baseline: 0.85 (0.89) for eli-cel-treated and 0.81 (0.86) for allo-HSCT-treated patients.

CONCLUSIONS : In the absence of preference-based utilities, PedsQL data can be used to provide credible estimates of health utilities for CALD patients receiving gene therapy or allo-HSCT.