Adults with spinal muscular atrophy (SMA) who began being seen at specialty centers after the approval of Spinraza (nusinersen) may have more severe symptoms than adults who have been followed regularly at such centers, a new study suggests.
The study, “Sometimes they come back: new and old SMA adults in the era of nusinersen,” was published in the European Journal of Neurology.
In recent years, the first disease-modifying treatments for SMA have been approved and made available. The first such treatment was Biogen‘s Spinraza, first approved in the U.S. in 2016 and in Europe in 2017.
Although most clinical trials for Spinraza have been conducted on children with the disease, the medication is widely approved for use in adults, too. While real-world data can provide some clues as to how effective this treatment is for adults, the heterogeneity of SMA — that is, the amount of person-to-person variation in how the disease manifests — makes it difficult to draw firm conclusions from real-world data.
Further complicating matters, at many centers, the approval of new SMA treatments was followed by an increase in contact from adults with SMA who previously had been unknown to SMA healthcare networks. It’s unclear whether there are meaningful differences between adults with SMA who have been followed for a long time, and those who only recently contacted clinics after treatments became available.
“We describe the clinical and demographic features of a large adult cohort with SMA reporting our experience of the ‘new’ patients who came to clinic at the time new treatments became available, trying to establish possible differences with the adult patients regularly followed in our clinics,” the researchers wrote.
These researchers analyzed data for 166 adults (78 female and 88 male) with SMA, collected from five healthcare centers in Italy. Of the 166 people analyzed, one had SMA type 1, 65 had type 2, 99 had type 3, and one had type 4. The age of the analyzed group ranged from 18.02 to 74.39 years; the mean age was 37.09 years. The mean disease duration was 33.56 years.
Of the 166 people analyzed, 99 had been followed regularly at the centers prior to the arrival of Spinraza. The remaining 67 (34 females and 33 males) “came to our clinics with the main purpose of having information on the nusinersen [Spinraza] treatment accessibility,” the researchers wrote.
Although none of the newcomers were being followed regularly at the time they arrived at the centers, all of them reported having been followed at pediatric centers previously. Of the newcomers, one was type 1, 20 were type 2, and 46 were type 3.
“When transitioning from the pediatric to the adult age, most of them, had gradually lost interest to attend specialist centers,” the researchers wrote. “Patients often complained that the assessments performed by adult neurologists were less detailed and there was less physiotherapist input compared to the pediatric setting.”
There were no statistically significant differences in age or disease duration between newcomers and the regularly-followed patients.
Among individuals with type 2 SMA, significantly more newcomers than regularly followed patients had lost the ability to sit (90% vs. 44.4%).
In the overall group, regularly-followed patients had higher scores than newcomers on the Revised Upper Limb Module (RULM) and the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE) — two measures of physical function, where higher scores indicate better functionality. Analyzed by type, the difference in scores for both assessments was statistically significant among people with SMA type 2, but not among those with SMA type 3.
“There was a higher proportion of newcomers who were in the severe end of the spectrum of type II , compared to the regularly followed,” the researchers wrote.
Regularly-followed patients tended to have better lung function than newcomers; however, the difference did not reach statistical significance. There was a statistical significance in the frequency of noninvasive ventilation use, which was more common among regularly-followed patients than newcomers.
“There was a limited number of patients using any form of ventilation in the newcomers’ group, despite many of them being aware of clinical signs and in some cases, also of abnormal sleep studies,” the researchers wrote.
According to researchers, newcomers said they “felt in good health” and did not want to wear a mask at night. However, seven of these individuals began ventilation once they started being followed regularly.
There were no significant differences in the frequency of scoliosis surgeries, or in nutritional status, between newcomers and regularly-followed patients.
About half (51.51%) of the regularly-followed patients were being treated with Spinraza, as were about a third (31.34%) of the newcomers. In both groups, the mean treatment duration was about one-and-a-half years.
The researchers noted that most newcomers agreed to be followed regularly, even if they didn’t start treatment.
“In this study we present a snapshot of a large cohort of Italian adult patients with SMA, focusing on those who were, until recently, not followed in tertiary care center,” the researchers wrote.
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