OBJECTIVES:

This study aimed to assess the psychometric properties of the EQ-5D-5L and the preference-based PROMIS Preference score (PROPr) and compare their performance in Chinese patients with Spinal muscular atrophy (SMA).

METHODS:

Data used in this study were obtained via a web-based survey coordinated by a national SMA patient organization in 2021. Individuals who were formally diagnosed with SMA, and aged ≥ 16 years were invited to complete the EQ-5D-5L and PROMIS-29, as well as questions assessing their demographics, socioeconomics, and health status. Acceptability (missing data, ceiling and floor effects), convergent and divergent validity (Spearman's correlation coefficient), and known-group validity (analysis of variance) of the EQ-5D-5L and PROMIS-29 and their agreement (intra-class correlation coefficient [ICC]) were assessed.

RESULTS:

A total of 137 individuals (Age: 16 ~ 47 years; female: 52.6%) with SMA completed the questionnaires. Ceiling effects were observed for four dimensions of the EQ-5D-5L ranging from 29.2% (usual activities) to 49.6% (self-care); no participant reported the best (11111) or worst health state of the EQ-5D-5L. Regarding PROMIS-29, significant floor effects were observed for the subscale of pain intensity VAS (27%), pain interference (32.1%), and physical function (45.3%). All hypothesized associations between EQ-5D-5L/PROMIS-29 and PedsQoL core questionnaire or neuromuscular module were confirmed, and dimensions of the EQ-5D-5L were significantly correlated with corresponding subscales of the PROMIS-29 (e.g., r mobility-physical functioning=-0.72 and r pain/discomfort-pain intensity=0.51), supporting convergent validity. Both EQ-5D-5L and PROPr scores differentiated between impaired functional groups, demonstrating good discriminative ability.

CONCLUSIONS:

The EQ-5D-5L and PROPr assessed by the PROMIS-29 are valid preference-based measures for individuals with SMA. The PROPr yields a considerably lower utility score than the EQ-5D-5L in this patient group. Their performance should be further explored in the other rare disease groups.