OBJECTIVES: Metachromatic leukodystrophy (MLD) is a rare lysosomal storage disease caused by deficient arylsulfatase A activity, leading to progressive cognitive and motor dysfunction and death. We estimated late-infantile MLD (LI-MLD) patient and caregiver health state utilities to inform cost–utility evaluations of MLD treatments. Utilities range from 1 (full health) to 0 (dead); values <0 reflect states considered worse than dead.

METHODS:

Patient and caregiver health states were defined using the Gross Motor Function Classification in MLD (GMFC-MLD; level [L]0–6), the Expressive Language Function Classification in MLD (ELFC-MLD; L0–4) and feeding/breathing support dependency. Health state vignettes were developed through a literature review and interviews with caregivers and clinicians of patients with LI-MLD. Valuation of the vignettes was conducted using time trade-off (TTO) and/or EQ-5D-5L valuation exercises with adults in the general population (UK) and caregivers and clinicians of children with LI-MLD or another pediatric progressive neuromuscular disease (US and UK).

RESULTS:

TTO-based and EQ-5D-5L-based utility values for patient states decreased from 0.754 and 0.693 (GMFC-MLD L1: ‘walking without support but unstable’) to −0.356 and −0.418 (GMFC-MLD L6: ‘no locomotion nor head control’), respectively. Caregiver state utility values decreased from 0.928 and 0.864 (caring for patients at GMFC-MLD L1) to 0.454 and 0.246 (caring for patients at GMFC-MLD L6), respectively. Utility values for ELFC-MLD modestly affected valuations. These were influenced by GMFC-MLD level: moving from ‘normal’ to ‘reduced-quality’ sentences showed a larger disutility at GMFC-MLD L1 than L3. Feeding/breathing support dependency were not important drivers of patient health state valuations at GMFC-MLD L4–5.

CONCLUSIONS: Living with LI-MLD and caring for a child with LI-MLD carries substantial burden. Gross motor function impairments were associated with the greatest decline in utility; communication impairments were associated with modest disutilities. These findings highlight the potential benefit of treatments that delay disease progression.