OBJECTIVES: Spinal muscular atrophy (SMA) is a rare, inherited neuromuscular disease. The primary study objective was to evaluate UK caregiver and patient preferences for treatment attributes in Type 2 and non-ambulatory Type 3 SMA. A secondary objective was to measure caregiver health-related quality of life (HRQoL).

METHODS: A targeted literature review and expert consultations were used to inform attribute selection and develop attribute descriptions for a discrete choice experiment (DCE). The DCEs for patients and caregivers included the following attributes: motor function, respiratory function, mode of administration, treatment reactions, requirement for ophthalmologic monitoring and need for contraception (adult patients only). An orthogonal fractional factorial array was used to design the DCE choice sets. A conditional logit model with clustering by respondent was used to estimate strength of preference for each attribute. Caregiver HRQoL was measured using the EQ-5D-5L. Disutilities were estimated using linear regression with robust standard error calculations.

RESULTS: Data from 84 patients and 83 caregivers were included. The model results indicated that caregivers valued improved motor function the most, followed by improved respiratory function. In contrast, patients placed most value on stabilizing/avoiding worsening respiratory and motor function. Both caregivers and patients preferred oral treatment over intrathecal injections. Finally, as opposed to patients, caregivers also made choices to avoid longer-lasting treatment reactions. The need for ophthalmologic monitoring and contraception did not have significant effects on caregiver or patient choices. The average caregiver EQ-5D-5L utility score was 0.940 (standard deviation=0.091). Small disutilities were associated with providing care for pediatric patients with worse motor and respiratory functions.

CONCLUSIONS: The study results indicate that caregivers made more trade-offs to improve motor and respiratory function, whilst patient choices were more strongly driven by avoiding worsening respiratory and motor function. Both caregivers and patients preferred the use of an oral treatment.