Development of the SMA independence scale–upper limb module (SMAIS–ULM): A novel scale for individuals with Type 2 and non-ambulant Type 3 SMA

Abstract

Background: The amount of assistance required to perform daily activities for individuals with Type 2 and nonambulant Type 3 spinal muscular atrophy (SMA) is often cited as meaningful for quality of life, and important to routinely assess. Methods: The SMA Independence Scale (SMAIS), a patient-reported outcome measure for individuals with SMA aged ≥12 years, and an observer-reported outcome measure for caregivers of individuals aged ≥2 years, was developed and evaluated in two phases. In Phase 1, 30 draft items were developed following review of the literature. Semi-structured interviews were then conducted with individuals with SMA and caregivers to establish content validity, resulting in a 29-item measure. In Phase 2, classical test theory and Rasch measurement theory methods were used to examine the cross-sectional and longitudinal measurement performance of the SMAIS in two independent datasets. Results: Phase 1 qualitative findings supported the relevance, acceptability, and comprehensibility of 29 items. In Phase 2, psychometric analyses indicated that the five response options were poorly discriminated and were thus collapsed to three options for subsequent analyses. Items showed statistical misfit, implying that the SMAIS was not assessing a single underlying construct. Based on conceptual evaluation of the items, and assessment of item performance, a more targeted 22-item upper limb score was derived. Reliability and validity analyses confirmed acceptable measurement properties of this score. Conclusions: Qualitative and quantitative analyses support the use of the 22-item SMAIS-Upper Limb Module in individuals with Type 2 and non-ambulant Type 3 SMA, aged ≥2 years.

Two-year efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA)

“…The progressive improvement on the RULM scale (1.91 at month 12, 2.06 at month 18, and 2.79 at month 24) following risdiplam treatment in this study exemplifies the impact of risdiplam on upper limb function. Increases in the caregiver-reported SMAIS-ULM total score (1.68 at month 12, 2.10 at month 18, and 2.73 at month 24; available for the full population), which is strongly correlated with the RULM [ 19 ], also corroborate the consistent effect of risdiplam on upper limb function in this population. Taken alongside numerical increases in the HFMSE total score and the patient-reported SMAIS-ULM that were also observed at month 24, this provides evidence that risdiplam is providing benefit to treated patients relative to untreated control patients.…”

“…The 24-month exploratory objectives and outcomes included the efficacy of risdiplam treatment with regard to motor function (as measured by MFM32 [ 16 ], Hammersmith Functional Motor Scale—Expanded [HFMSE] [ 17 ], and Revised Upper Limb Module [RULM] [ 18 ]); respiratory function (as measured by sniff nasal inspiratory pressure, maximal inspiratory pressure, maximal expiratory pressure, forced vital capacity [FVC], forced expiratory volume in the first second, and peak cough flow); patient- and caregiver-reported independence (as measured by the SMA Independence Scale-Upper Limb Module [SMAIS-ULM] [ 19 ]); and safety and tolerability. The scoring methods for each endpoint in this study have been described previously [ 13 ].…”

Validation of a Set of Instruments to Assess Patient- and Caregiver-Oriented Measurements in Spinal Muscular Atrophy: Results of the SMA-TOOL Study

“…The SMAIS is a 29-item self-reported questionnaire to assess the ability of patients with SMA type 2 or 3 to independently perform activities of daily-living [ 21 , 22 ]. The SMAIS has a patient version for patients aged 12 years or over and a caregiver-report version for caregivers of patients aged over 2 years.…”

A Patient-Centered Evaluation of Meaningful Change on the 32-Item Motor Function Measure in Spinal Muscular Atrophy Using Qualitative and Quantitative Data

“…Improvement on the SMAIS-ULM reported by caregivers defined as ≥3 points in 22-item upper limb total score ( 24 ).…”

“…• Improvement (i.e., combined minimally, much and very much improved groups) on the CGI-C. • Improvement on the RULM defined as ≥2 and ≥3 points in RULM total score (27,28). • Improvement on the SMAIS-ULM reported by caregivers defined as ≥3 points in 22-item upper limb total score (24). • Improvement on the EQ-5D-5L self-care item reported by caregivers defined as improved by ≥1 point.…”