Measuring Fatigue and Fatigability in Spinal Muscular Atrophy (SMA): Challenges and Opportunities

Abstract

Fatigue, a common symptom, together with the characteristic of performance fatigability, are well-documented features of SMA that impact quality of life and function. Importantly, establishing associations between multidimensional self-reported fatigue scales and patient performance has proven difficult. This review was conducted to evaluate the various patient-reported fatigue scales applied in SMA, with the objective of considering the limitations and advantages of each measure. Variable use of fatigue-related nomenclature, including conflicting terminology interpretation, has affected assessment of physical fatigue attributes, specifically perceived fatigability. This review encourages the development of original patient-reported scales to enable perceived fatigability assessment, providing a potential complementary method of evaluating treatment response.

Keywords: fatigability; fatigue; patient-reported outcome measure; perceived fatigability; spinal muscular atrophy.

Figure 1

(A) Different dimensions of fatigue commonly studied in SMA (yellow). (B) Constructs related to the physical fatigue dimension, which are assessed by some PROs (purple). (C) Attributes of physical fatigue: (1) performance fatigability (light blue) and (2) perceived fatigability (gray). (D) Fatigue confounders (green). Two-way arrows represent relationships; they provide a theoretical framework for conceptualizing (physical) fatigue, performance fatigability, and perceived fatigability as interrelated concepts that likely interact and influence each other during physical activity.