- What is the clinical effectiveness of nusinersen in adolescents and adults with spinal muscular atrophy?
Five observational descriptive studies were included in this report. Four of the included observational studies had relatively small sample sizes ranging from six patients to 19 patients. One of the observational studies had a larger sample size (total of 172 patients enrolled), but only provided an analysis at month 14 for 57 patients. Overall, these studies indicated improvements were reflected in the Hammersmith Functional Motor Scale Expanded score, to a lesser extent on the Revised Upper Limb Module score, and mixed scores of improvements, stabilization, and decline in the 6-Minute Walk Test across the studies. Safety was reported in two of the included studies with three events registered as severe.
Limitations of the available evidence revolve around the study design and missing data. The study design (observational and uncontrolled) prevents any sort of statistical inference to be made from the generally small samples within the studies. In addition, several biases are likely to have had an effect in favour of nusinersen, including: selection bias, expectation bias, and attrition bias.
The review cannot answer the question of the clinical effectiveness of nusinersen in adolescent and adult patients with SMA because of the significant limitations of the included studies. The included evidence serves as exploratory information for the formulation of a scientific hypothesis to be tested within a controlled clinical trial study design.