Spinraza Doses Largely Given as Advised, Real-world US Data Show
People with spinal muscular atrophy (SMA) being treated with Spinraza (nusinersen) received most of their injections at recommended times, according to real-world data from two large U.S. databases.
In an electronic health records (EHR) database, adherence to treatment was similar in the maintenance and loading phase of Spinraza, but it was higher during the maintenance phase in an insurance claims database. Analyses suggest that “not all loading doses of nusinersen may be accurately captured in the claims databases,” the researchers wrote.
“Our findings highlight the challenges of obtaining valid findings in real-world adherence or treatment patterns research when the full dosing history is not completely captured in administrative databases,” they added.
The study, “Examining Real-World Adherence to Nusinersen for the Treatment of Spinal Muscular Atrophy Using Two Large US Data Sources,” was published in the journal Advances in Therapy.
Spinraza is administered via intrathecal, or spinal canal, injection
Spinraza, marketed by Biogen, was the first disease-modifying therapy approved to help slow and potentially stop SMA progression. Administered directly into the spinal canal — a procedure called an intrathecal injection — the treatment works to increase levels of the SMN protein in cells, which are low in people with SMA.
As approved, administration of Spinraza begins with four loading doses — three given at two-week intervals, and a fourth given one month later — after which patients receive maintenance doses every four months.
Adherence to this dosing schedule is key for Spinraza’s effectiveness. However, whether patients take the therapy as prescribed and remain on treatment in a real-world setting is questionable, with studies showing conflicting results.
Retrospective data from patients treated at the Muscular Dystrophy Association’s care centers in the U.S. showed that most doses were received according to Spinraza’s dosing schedule, but studies based on data from U.S. insurance claims have suggested low treatment adherence.
However, these commercial insurance claims often lack a complete list of prescribed medications, which “may lead to inaccuracies in calculating patient adherence or treatment-related outcomes,” the researchers wrote.
To evaluate real-world adherence to Spinraza, a team led by researchers at Biogen used data from two large U.S. databases, the Optum EHR database and the Merative MarketScan Research Databases, which includes commercial insurance and Medicaid claims.
Findings from the EHR database covered the period between July 1, 2017, and Sept. 30, 2019. The period for the Marketscan databases ranged from Jan. 1, 2017, to June 30, 2020, for the commercial insurance claims, and from Jan. 1, 2017, to Dec. 31, 2019, for Medicaid claims.
Patients in the EHR database were required to have at least six months of recorded data prior to first use of Spinraza.
More than 80% of Spinraza doses shown to be given on time in US databases
In total, the analysis included 358 SMA patients — 67 patients from the EHR and 291 from the two claims databases. Of the latter group, 170 patients (58.4%) were in the commercial insurance database, and 121 (41.6%) in the Medicaid database.
Patients in the EHR database had a mean age of 23.5 when they received their first Spinraza dose, while those in the claims databases were 17.9 years old on average. Adults comprised about half of patients in both the EHR database (53.7%) and the claims databases (45.4%).
Overall, patients in the EHR and claims databases received a mean of five Spinraza doses. Only those who received at least two doses — 89.6% of patients in the EHR database and 79% in the claims databases — were used in the treatment adherence analysis.
Results showed that the majority of doses were received on time — 93.9% of the doses registered in the EHR and 80.5% of those in the claims databases.
Patients in the EHR database maintained a similar adherence to Spinraza in the initial loading regimen and in the maintenance phase — with 92.6% and 95.5% of doses in each phase being given on time.
In contrast, patients from the claims databases showed a markedly higher adherence during the maintenance regimen (90.6%) compared with the initial loading phase (71.1%). This pattern was maintained when patients without six months of data prior to starting Spinraza were excluded from the analysis.
Data from both the EHR and claims databases also confirmed that Spinraza was administered within the expected interval between doses, both in its loading and maintenance phases.
Overall, this real-world analysis showed that Spinraza “doses were received on time, consistent with the recommended schedule,” the researchers wrote.
“The different findings in the claims analyses suggest that … not all loading doses of nusinersen may be accurately captured in the claims databases,” they added, noting challenges in these administrative databases. “Prevalent users (or existing users of nusinersen) who are already on maintenance doses may be misclassified as incident users (or new users of nusinersen) on loading doses, resulting in lower reported adherence during the loading dose phase.”
As such, “our findings also highlight the importance of careful methodological approaches when using real-world administrative databases for evaluation of nusinersen treatment patterns,” their study concluded.
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