Measuring the SMA Experience

Each evening, millions of people around the world sit at dinner tables, pick up forks, spoons or chopsticks, and lift the utensils to their mouths without thinking twice about it. But what would it feel like if any step in the sequence became impossible to perform?

It’s a scenario almost every researcher at Genentech and Roche working in the area of spinal muscular atrophy (SMA) is aware of and working to address. We’ve seen first-hand how people living with this rare neuromuscular condition experience a range of symptoms and physical limitations that can severely impair their quality of life. And we’re working hard to further our understanding of the challenges people living with SMA face on a daily basis.

The ability to measure and monitor a disease is critical to understanding how it impacts a person living with the condition. Over many years, researchers and clinicians have created scales to assess functional ability and motor function in people living with SMA—everything from fine motor tasks (such as fastening buttons), to core function (such as leaning forwards and backwards), to lower limb function (such as walking). We’re working to evaluate these scales and select those measuring outcomes that are relevant and meaningful to people living with SMA.


SMA affects people in different ways, depending on the type, age group and other factors. This variability among different types of SMA demands thoughtful outcome measure selection, data collection and analysis on the part of researchers. Certain key milestones, including sitting, standing or walking, are more objectively measured and observed, compared to smaller but still meaningful changes in motor function ability (e.g., reduced ability to perform typical daily activities). Evaluating different measurement scales for different types of people living with SMA to pinpoint the most relevant outcome measures is a fundamental part of understanding disease progression—particularly where small changes in function can have marked impact on an individual’s ability to perform daily tasks.


The number of measurement scales available to SMA researchers today reflects the commitment and dedication of the global research community. For SMA Types 2 and 3, the list includes the Motor Function Measure (MFM-32), Hammersmith Functional Motor Scale-Expanded (HFMSE), Revised Upper Limb Module (RULM), and the SMA Independence Scale (SMAIS)—among numerous other assessment tools.

Together these scales provide important insights into motor function ability and impacts on daily life. Nevertheless, there’s an ongoing need to improve measurement precision, especially given the variability in level of impairment across the spectrum of SMA Types 2 and 3.

Starting about four years ago, we began qualitative research that captured both objective and subjective experiences for children, teens and adults living with Types 2 or 3 SMA—everyday activities such as feeding oneself, turning a page in a book or moving around in a wheelchair. The goal was to select measures sensitive enough to detect meaningful disease progression or slowing of progression in a clinical trial setting.

One such scale is the Motor Function Measure 32 (MFM-32), which evaluates 32 different motor functions, such as head support, hip and knee flexion, upper limb function, sitting, standing, finger and wrist movement, walking, running and hopping. The scale is able to measure motor function across a broad spectrum, from those who are very weak (with impaired distal motor function) up to those who still have some ambulatory function.

In our qualitative research, many individuals and caregivers emphasized their desire to maintain independence. In this regard, for many people living with SMA, being able to grasp an object can make a meaningful difference in a person’s level of independence in their everyday life—for example, being able to dress or feed themselves. With this in mind, we developed the SMA Independence Scale (SMAIS), which measures the amount of assistance required to perform typical daily activities, such as getting dressed or self-feeding. Click here to learn more about other measurement scales for SMA.


Cure SMA, a patient advocacy organization dedicated to the treatment and cure of SMA through research and resources for families, provided their expertise on this scale from the start. The organization identified families affected by the illness and facilitated our outreach. This was especially helpful as we worked to develop the SMAIS scale.

We conducted two rounds of qualitative research. The first round was conducted to identify the symptoms and impacts associated with Types 2 and 3 SMA, from the perspective of individuals with SMA and their parents. We collaborated with other companies researching SMA to make sure individuals participating in the study and their families would not be asked to participate in multiple interview studies. We also believe that close collaboration within the SMA community will yield more valuable research insights.

The second round of qualitative research was conducted to gain direct feedback on the draft SMAIS. From these interviews with individuals with SMA and their families, we identified new questions to add, and existing questions to modify, to ensure we are measuring what matters in a clear and comprehensive manner. We are now testing the measurement properties of the SMAIS to see if it’s a valid (accurate) and reliable (consistent) measure of the amount of assistance required to perform typical daily activities. The ultimate aim is to provide the community with a useful and meaningful patient- and caregiver-reported measure for use in clinical studies and beyond.

Above all, we want to understand the experience of living with SMA and be confident the scales we use accurately capture information that matters to people with the condition. Like any serious illness, supporting people with SMA and their loved ones begins with taking a “listen first” approach, and optimizing clinical studies to best serve the unique needs these people face.