Kids with Spinal Muscular Atrophy Rate Their Own Health
—A new study analyzed health-related quality of life (HRQoL) using 5 generic and neuromuscular disease-specific rating scales in German children with spinal muscular atrophy (SMA), most of whom were receiving disease-modifying therapies.
According to a new study, children with spinal muscular atrophy (SMA) reported good health-related quality of life (HRQoL), although results varied widely among rating scales.1
Previous studies have found that HRQoL may be impaired in patients with SMA—not surprising given the condition’s potential severity.2-4 However, “little is known of the self-assessed HRQoL of patients with SMA in the era of disease-modifying therapy,” Erik Landfeldt, MSc, PhD, an epidemiologist at IQVIA in Stockholm, said in an interview with app. Studies on HRQoL in children with SMA, he added, are particularly lacking.
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This knowledge gap is a problem for several reasons, Dr. Landfeldt says: “It’s important for physicians, caregivers, researchers, and decision-makers to understand how individuals with SMA are doing in terms of HRQoL, to help inform medical management, support schemes, and the like, and also how different measures of HRQoL work in SMA, to inform instrument selection for future research.”
To get an up-to-date assessment of HRQoL among children with SMA, Dr. Landfeldt and his fellow researchers conducted a pilot study, the aim of which was to estimate HRQoL using 5 commonly utilized rating scales.1
How the study was designed
Children with SMA were identified in the German national TREAT-NMD SMA patient registry.1 To be eligible for the study, genetic confirmation of SMA, age of 5 or more years, and German residency were required.
Children completed 4 generic and 1 neuromuscular disease-specific rating scales:
- KIDSCREEN-27: a generic scale with ratings of 0 to 100, for children ages 8 to 17 years. Domains include physical and psychological well-being, autonomy and parents, peers and social support, and school environment.
- KINDL: a generic scale with ratings 0 to 100, for kids ages 5 to 7 years. Domains include physical and emotional well-being, self-esteem, family, friends, and school.
- Pediatric Quality of Life Inventory (PedsQL) 3.0 Neuromuscular Module (PedsQL 3.0 NMM): a neuromuscular disease-specific scale with ratings 0 to 100, for those ages 5 to 17 years. Children are asked to rate their neuromuscular disorder and levels of communication and family resources.
- EQ-5D-5L: a generic scale for children ages 12 to 17 years, covering mobility, self-care, usual activities, pain, discomfort, anxiety, and depression. The scale ranges from –0.661 to 1.00, with a negative score equating to a state of health that’s worse than being dead, 0 equal to being dead, and 1 equal to perfect health.
- Health Utilities Index (HUI) Mark III: a generic scale for those ages 8 to 17 years. Domains include vision, hearing, speech, ambulation, dexterity, emotion, cognition, and pain. The scale ranges from –0.36 to 1.00, with a negative score meaning worse than being dead, 0 equal to being dead, and 1 equal to perfect health.
Participants were stratified by SMA type and current lower limb and trunk function into 3 groups: nonsitters, sitters, or walkers.
Participant characteristics at a glance
Seventeen questionnaires were returned between June and September 2021. Most participants (59%) were female, and the mean age of the total cohort was 9.88 (standard deviation [SD] 4.33) years (range 5 to 16 years).
All types of SMA and current function were represented in the study. Four participants (24%) were nonsitters. Three of them had SMA type II and 1 had SMA type III. Seven participants (41%) were sitters, including 3 with SMA type I and 4 with SMA type II. Six participants (35%) were walkers; of these, 1 had SMA type II and the remaining 5 had SMA type III.
Fifteen out of 17 participants were receiving either nusinersen or risdiplam.
How the rating scales stacked up
KIDSCREEN-27. Ten children ages 8 to 16 years completed the KIDSCREEN-27 scale. Their mean score was 58.43 (SD 15.44; range 40.24 to 83.81). The researchers considered scores below 40 or above 60 to be outside the reference scores from the general population. So, in this case, the SMA study population had good HRQoL. The only mean scores lower than 40 were for the physical well-being subscale, among nonsitters (mean 35.41; SD 4.93; range 28.13 to 38.47) and those with SMA type II (mean 34.83; SD 5.26; range 28.13 to 40.45). Most participants rated their health as good, very good, or excellent.
KINDL. Seven children ages 5 to 7 years completed the KINDL screen. Their mean score was 72.02 (SD 12.16; range 45.83 to 83.33), with higher scores corresponding to better HRQoL. The mean KINDL score was 68.05 (SD 19.69; range 45.83 to 83.33) for walkers and 60.42 (SD 20.63; range 45.83 to 75.00) for participants with SMA type III.
PedsQL 3.0 NMM. All 17 participants completed the PedsQL 3.0 NMM, with a mean score of 73.88 (SD 19.52; range 29 to 99). Nonsitters had lower scores in each domain compared with sitters and walkers.
EQ-5D-5L. Seven participants ages 12 to 16 years completed the EQ-5D-5L utility rating. The mean score was 0.54 (SD 0.31; range 0.30 to 1.00) but varied by functional status group. Walkers rated their health status as close to perfect, with a mean score of 0.99 (SD 0.02; range 0.97 to 1.00). However, for nonsitters and sitters, mean scores were lower: 0.35 (SD 0.06; range 0.30 to 0.39) and 0.37 (SD 0.06; range 0.31 to 0.42), respectively.
The EQ-5D-5L also included a visual analog scale (VAS) score of 0 to 100 for health status, from the worst (0) to the best imaginable (100). The mean VAS score was 87.50 (SD 3.54; range 85.00 to 90.00) for nonsitters and 64.67 (SD 25.01; range 40.00 to 90.00) for sitters. Walkers rated their health status as 90.00 (SD 0.00; range 90.00 to 90.00) on the VAS.
HUI Mark III. The 10 participants who completed the HUI scale had a mean score of 0.44 (SD 0.40; range -0.02 to 1.00). As with the EQ-5D-5L utility scale, walkers had much higher average scores than other groups: 0.96 (SD 0.08; range 0.87 to 1.00), compared to 0.23 (SD 0.27; range 0.08 to 0.63) for nonsitters and 0.21 (SD 0.20; range -0.02 to 0.34) for sitters.
Which scale should clinicians use?
Dr. Landfeldt and his colleagues say that the main limitation of their study was its small sample size, which could affect estimates. The small size also prevented them from evaluating the effects of specific therapies on HRQoL. Another limitation concerned generalizability, in that the study included patients from only 1 country with a robust healthcare system. And, finally, self-reports can be biased.
“Our preliminary findings show that German children with SMA, despite significant physical disability, have surprisingly good subjective HRQoL,” Dr. Landfeldt says. “However, our results also reveal that self-assessed HRQoL in SMA varies substantially depending on the rating scale used, as well as across categories of current best motor function and SMA type.”
Although children with SMA gave high HRQoL ratings on the KIDSCREEN-27, the question of which rating scales are the most informative is complex. As Dr. Landfeldt explains, “It’s worth noting that HRQoL is a latent, hidden trait, which can’t be measured directly in the same way we can measure weight or height.” As such, the variation among rating scale methodology accounts for a large source of the variation in HRQoL estimates.
To get a clearer picture, Dr. Landfeldt says, future studies on HRQoL with pediatric SMA patients will require larger studies with sufficient sample sizes representing a range of motor functions and SMA types.
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