The Spinal Muscular Atrophy Health Index: A novel outcome for measuring how a patient feels and functions

Abstract

Introduction:The Spinal Muscular Atrophy Health Index (SMA-HI) is a multifaceted, disease-specific, patient-reported outcome to measure an SMA patient's perception of their disease burden. In preparation for upcoming therapeutic trials, we examine the validity, reliability, and usability of the SMA-HI in adults, teenagers, and children with SMA.Methods: Using data from a cross-sectional study of 359 international adult patients with SMA, we identified the most relevant symptoms to include in the SMA-HI. We utilized factor analysis, patient interviews with adults and minors (age 8-15 years), known-group validity testing, and test-retest reliability assessments to evaluate and refine the SMA-HI. Results:The SMA-HI measures overall disease burden and 15 areas of SMA health.Fifteen adult patients and five patients, age 8 to 15 years, participated in semistructured qualitative interviews and found the SMA-HI to be comprehensive, easily completed, and to have clear meaning. The final SMA-HI and its subscales demonstrated good internal consistency (Cronbach α = 0.77-0.96), high test-retest reliability (intraclass correlation coefficient = 0.60-0.96), and an ability to differentiate between SMA groups with different disease severities affecting areas such as employment and ambulation (P < .0001 for both).Discussion: This research provides evidence that the SMA-HI is a valid, relevant, and reliable outcome measure to assess multifaceted patient-reported disease burden in older children, teenagers, and adults with SMA. The SMA-HI provides an opportunity for researchers and clinicians to measure a SMA patient's perception of their health and determine relevant changes in response to therapeutic intervention or disease progression.

Assessing perspectives of disease burden and clinically meaningful changes using the Spinal Muscular Atrophy Health Index in adolescents and young adults

“…As in previously published studies, 9,10 results of the current analysis confirm that SMA‐HI scores increase with increasing disease severity. In the previous cross‐sectional study involving 359 adults with SMA (mean age = 42 y; range, 18–81 y), the results were stratified by age group (18 to <42 y vs ≥42 y).…”

“…In the previous cross-sectional study involving 359 adults with SMA (mean age = 42 y; range, 18-81 y), the results were stratified by age group (18 to <42 y vs ≥42 y). Compared with these older-age cohorts, 9 results from the current study found that younger populations (aged 12-25 y) generally had lower SMA-HI total and subscale scores. 9 This finding may suggest an association between older individuals with SMA, higher disease burden, and increased SMA-HI scores.…”

“…Compared with these older-age cohorts, 9 results from the current study found that younger populations (aged 12-25 y) generally had lower SMA-HI total and subscale scores. 9 This finding may suggest an association between older individuals with SMA, higher disease burden, and increased SMA-HI scores. While participants in the two studies were recruited using different mechanisms at different times, in general, lower scores were observed in the current adolescent/young adult cohorts compared with previously studied adults with SMA.…”

Assessment of Health-Related Quality of Life in Adult Spinal Muscular Atrophy Under Nusinersen Treatment—A Pilot Study

“…Besides, they do not represent motor functions not related to the extremities like swallowing which are nevertheless important for the patients' QoL. Recently, the Spinal Muscular Atrophy Health Index (SMA-HI) has been proposed as a novel means to capture the disease burden from a patient's perspective ( 36 ). Apart from that, treatment expectations have been shown to be even higher in less severely affected individuals ( 37 ), and other individual psychological factors ( 38 ) might have influenced the patient-reported QoL in our study.…”

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

“…PedsQL Neuromuscular Module [ [70]], Assessment of Caregiver Experience in Neuromuscular Disease (ACEND) [21], Pediatric Evaluation of Disability Inventory-Computerized Adaptive Testing (PEDI-CAT) [22]. Recent advances include the development of the SMA Health Index, a novel scale developed for use in Types 2 and 3 SMA [ [69]], but it does not directly assess independence.…”