Perceived Fatigue Not Linked to Physical Factors, Quality of Life in SMA Patients, Study Reports

The sense of fatigue perceived by patients with spinal muscular atrophy (SMA) does not correlate with their physical tendency to get tired, their motor function, or quality of life, a study reports.

According to this study, the feeling of being tired, or perceived fatigue, can be independent of the patient’s physical performance and depend on many other factors including those of a psychological nature.

The study, “Perceived Fatigue in Spinal Muscular Atrophy: A Pilot Study,” was published in the Journal of Neuromuscular Diseases.

Fatigue is a common and disabling complaint of many patients with neuromuscular diseases, including those with SMA.

This symptom encompasses two different domains: a subjective one, or perceived fatigue, that consists of a sense of tiredness, lack of energy, or feeling of exhaustion; and an objective one, dubbed performance fatigability, characterized by a measured decline in motor performance.

Perceived fatigue and fatigability “are not only different but potentially independent of each other,” according to the researchers.

Fatigability is well-described in SMA patients receiving ambulatory (outpatient) care, but perceived fatigue has been little investigated and measured, and its relationship with fatigability is largely unknown.

However, researchers believe that understanding this relationship and what contributes to perceived fatigue “would help to optimize rehabilitation programs,” which currently include medications for fatigue, rehabilitation or exercise, educational interventions, cognitive behavioral therapy, or a combination of all these.

Researchers at Columbia University assessed the feasibility of measuring perceived fatigue in children and adults with SMA and their caregivers and assessing the correlation between perceived fatigue and objective fatigability, motor function, and quality of life.

The study included 32 participants with SMA (21.9% type 2, 78.1% type 3), ages 5 to 49 years, recruited from a natural history study from the SMA Clinical Research Center at Columbia University Medical Center. Nearly half of the participants were hospitalized (non-ambulatory).

Patient- or parent-reported outcome measures were used to measure perceived fatigue, including the PedsQL Multidimensional Fatigue (MFS) Scale and the Fatigue Severity Scale (FSS).

Other standard questionnaires and assessments were used to measure fatigability (six-minute walk test), gross and arm motor function, and quality of life. Fatigability was only measured for participants on ambulatory care.

All SMA participants reported perceived fatigue, which was similar between those with SMA types 2 and 3.

A sense of tiredness and weakness was common among adults, with 78.6% of them reporting excessive or abnormal fatigue, and half complaining of severe fatigue.

Patients’ perceived fatigue was not associated with their motor function or quality of life, nor with fatigability in the ambulatory participants.

In addition, no associations were seen between age, SMA type, or ambulatory status and perceived fatigue.

Based on these results, the team believes that the two patient-reported outcome measures, the PedsQL MFS and the FSS, are suitable to quantify perceived fatigue in children and adults with SMA and may add value for clinical trials that target symptomatic treatment of fatigue in SMA.

These results add to the idea that a patient’s sense of fatigue can have many contributing factors, with the researchers concluding that “studies examining perceived fatigue should account for these important covariates, such as depression, pain, weakness, and sleepiness.”