Evaluating Benefit-risk Decision-making in Spinal Muscular Atrophy: A First-ever Study to Assess Risk Tolerance in the SMA Patient Community

Abstract

Purpose: Patients' perceptions of benefit-risk are essential to informing the regulatory process and the context in which potential therapies are evaluated. To bring this critical information to regulators, Cure SMA launched a first-ever Benefit-Risk Survey for spinal muscular atrophy (SMA) to characterize decision-making and benefit-risk trade-offs in SMA associated with a potential therapy. We hypothesized that risk tolerance would be correlated with SMA type/severity and disease progression. This article presents the results of a benefit-risk survey to enhance understanding of how patients with SMA and caregivers evaluate specific benefits and risks associated with potential therapies.

Methods: Affected adults, representing all SMA types (I-IV) within the Cure SMA database, and caregivers of affected individuals of all ages/types were invited via e-mail to participate. Best-worst scaling (BWS) was used to assess participants' priorities on benefit-risk trade-offs, as it provides higher discrimination and importance scaling among tested attributes. Twelve potentially clinically meaningful treatment benefits and 11 potential risks (ranging in severity and immediacy) were tested. Multiple factors were correlated with individual responses, including: SMA type/disease severity, stage of disease, respondent type, sex, and quality of life/level of independence (current and expected). Survey respondents were also evaluated for "risk-taking attitudes."

Findings: A total of 298 responses were evaluated (28% affected adults and 72% caregivers, mostly parents). Most respondents were diagnosed >5 years ago (67.3%), with 22.1% SMA type I, 45.6% SMA type II, and 27.9% SMA type III. No strong correlation was found between risk tolerance and SMA type, stage of disease progression, respondent type, sex, quality of life assessment, or rated levels of independence. Irrespective of SMA type, respondents consistently rated the following risks, associated with a potential treatment, as "least tolerable": life-threatening allergic reactions; 1 in 1000 risk of life-threatening side effects leading to possible organ failure; or worsening quality of life. Furthermore, all SMA type respondents rated these risks as "most tolerable": invasive mode of treatment administration (including need for general anesthesia); side effect of dizziness; and other common side effects such as nausea, vomiting, loss of appetite, headaches, back pain, or fatigue.

Implications: With the approval of the first SMA treatment, these findings offer a unique opportunity to assess and characterize baseline risk-tolerance in SMA against which to evaluate future SMA treatment options. Although differences had been expected in risk tolerance among respondents based on disease baseline and certain patient attributes, this was not observed. Survey results should inform future SMA drug development and benefit-risk assessments.

Keywords: benefit–risk assessment; best-worst scaling; drug development; patients and caregivers; rare disease; risk tolerance; spinal muscular atrophy (SMA).