We sought to describe real-world clinical outcomes and health care resource utilization (HCRU) in US patients with SMA aged ≥6 months when treated with nusinersen monotherapy, OA monotherapy, or switched to OA from nusinersen.

Disease-modifying treatments including nusinersen and OA have substantially improved SMA prognoses, but real-world data on treatment outcomes and HCRU are limited.

We conducted a retrospective chart review with outcomes summarized descriptively for patients at or before the index date (date of monotherapy initiation or switch to OA) who had medical information available for ≥1 follow-up visit. HCRU was summarized per patient-year (PPY). 

This analysis included 55 patients (19 nusinersen monotherapy; 21 OA monotherapy; 15 switching to OA from nusinersen). SMA phenotypes were type 1 (8/19; 4/21; 12/15), type 2 (8/19; 9/21; 1/15), type 3 (3/19; 5/21; 0/15), and undetermined (0/19; 3/21; 2/15), respectively. Improvement/maintenance of motor milestones from index was achieved by 8/19, 12/19, and 7/14 patients, respectively. Mean time to improvement (±SE) was 5.8 (1.4), 2.0 (0.4), and 4.7 (1.0) months, respectively. For patients treated with nusinersen monotherapy, OA monotherapy, or switching to OA from nusinersen, 12/19, 20/21, and 8/14 achieved/maintained normal cry function; 12/14, 18/18, and 9/11 improved/maintained speech function; and 10/17, 18/19, and 7/14 improved/maintained any eating function (e.g., thin liquids by mouth, some food consistency by mouth), respectively. Inpatient admission rates at baseline vs. follow-up were 1.06 vs. 0.65, 0.34 vs. 0.00, and 1.69 vs. 0.74; emergency room visits were 1.09 vs. 0.54, 0.26 vs. 0.34, and 1.25 vs. 0.50 PPY, respectively.

Patients with SMA improved/maintained function across multiple outcomes after receiving OA at ≥6 months of age, regardless of prior nusinersen therapy. Time-to-improvement for developmental milestones was shortest for patients who received OA monotherapy. Patients also experienced reductions in the rate of inpatient admissions, with no admissions after OA monotherapy.