Nonvolitional assessment of muscle endurance in idiopathic inflammatory myopathies: There is no relationship between patient-reported fatigue and muscle fatigability

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

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.

Effect of exercise training on fatigue and pain in patients with systemic autoimmune myopathies: A systematic review

Systemic autoimmune myopathies (or idiopathic inflammatory myopathies) are a wide group of rare rheumatic diseases characterized by muscle weakness due to muscle inflammation. Recent evidence has continually reinforced the relevance of the perception of pain and fatigue as parameters of notable contribution to reducing the quality of life of these patients. However, due to the multidimensional characteristic of these variables, few studies address the effects of pharmacological and non-pharmacological therapies, such as exercise training on these variables. With regard to patients with systemic autoimmune myopathies, the outcomes related to the effects of exercise training are focused on muscle strength and endurance, few explore the effects on the perception of pain and fatigue. Given this, studies that review systematically the available evidence of the effects of exercise training on these perceptions can contribute to management of this parameter in clinical practice. Given this context, the present study aims to review systematically the effectiveness of exercise training specifically on the perception of pain and fatigue.

Perceived Fatigue in Spinal Muscular Atrophy: A Pilot Study

BACKGROUND

Fatigue is a common complaint in spinal muscular atrophy (SMA). Fatigability is well described in ambulatory SMA but the relationship to perceived fatigue has not been evaluated. Understanding this relationship has proven challenging for most disorders.

OBJECTIVE

To assess the relationship of perceived fatigue to fatigability, function, and quality of life in SMA.

METHODS

Thirty-two participants with SMA (21.9% type 2, 78.1% type 3) were recruited. Perceived fatigue and fatigability, function, and quality of life were assessed using standardized questionnaires and assessments. Associations were analyzed using Pearson correlation coefficients (p = 0.05). Also, the effects of age, type, and ambulatory status were determined on perceived fatigue.

RESULTS

All SMA participants reported fatigue. Perceived fatigue was not associated with function, quality of life, or fatigability in ambulatory SMA patients. Neither age, type, nor ambulatory status influenced perceived fatigue.

CONCLUSIONS

Perceived fatigue can be quantified in SMA. Interestingly, perceived fatigue did not correlate with fatigability or function, suggesting that cognitive, homeostatic, or psychologic factors may be more relevant as co-morbid factors. Clinical trials targeting perceived fatigue in SMA should focus on these patient-reported assessments. A multilevel approach is required to separate the various mechanisms involved in perceived fatigue.

Does computed tomography-based muscle density predict muscle function and health-related quality of life in patients with idiopathic inflammatory myopathies?

OBJECTIVE

To investigate the association of low-density (lipid-rich) muscle measured by computed tomography (CT) with skeletal muscle function and health-related quality of life in idiopathic inflammatory myopathies (IIMs).

METHODS

Seventeen patients and 10 healthy controls underwent CT of the midthigh to quantify high- (30-100 HU) and low-density (0-29 HU) skeletal muscle areas. Anthropometric measures, body composition, physical activity level, health-related quality of life, skeletal muscle strength, endurance, and fatigue were assessed. Patients were compared against controls. The relationship of anthropometric, body composition, and disease variables with measures of muscle function were examined using Spearman's test on the patient group. Linear regression was used to assess the age- and disease-adjusted relationship of muscle quality to physical function and muscle strength.

RESULTS

Patients had higher body fat percentage (P = 0.042), trunk fat mass (P = 0.042), android:gynoid fat (P = 0.033), and midthigh low-density muscle/total muscle area (P < 0.001) compared to controls. Midthigh low-density muscle/total muscle area was negatively correlated with self-reported physical function, strength, and endurance (the Short Form 36 [SF-36] health survey physical functioning [P = 0.004], manual muscle testing [P = 0.020], knee maximal voluntary isometric contraction/thigh mineral-free lean mass [P < 0.001], and the endurance step test [P < 0.001]), suggesting that muscle quality impacts function in IIM. Using multiple linear regression adjusted for age, global disease damage, and total fat mass, poor muscle quality as measured by midthigh low-density muscle/total muscle area was negatively associated with SF-36 physical functioning (P = 0.009).

CONCLUSION

Midthigh low-density muscle/total muscle area is a good predictor of muscle strength, endurance, and health-related quality of life as it pertains to physical functioning in patients with IIMs.

Physical impairment in patients with idiopathic inflammatory myopathies is associated with the American College of Rheumatology functional status measure

The goals of this study were to assess the predictive value of chart-abstracted American College of Rheumatology functional status (ACR-FS) with patient-reported ACR-FS and to relate it with measures of muscle function in a single-institution cohort of patients with idiopathic inflammatory myopathies (IIMs). Demographic and clinical data of 102 patients with IIMs regularly followed in the Rheumatology and Neurology Clinics at the University of Kentucky Medical Center between 2006 and 2012 were obtained through retrospective chart review. Clinical and functional status evaluation, muscle performance testing, and body composition measures were performed on a subset of 21 patients. ACR-FS was obtained by both chart abstraction and direct patient report. Spearman's correlations were used to examine the relationship of ACR-FS derived from chart abstraction with direct patient report, as well as the relationship of measures of physical function and body composition with ACR-FS. ACR-FS derived from chart abstraction was significantly correlated with ACR-FS derived from direct patient report (ρ = 0.78, p < 0.001). ACR-FS derived from chart abstraction was also significantly correlated with patient-reported physical function (ρ = -0.71, p < 0.001) and physical activity (ρ = -0.58, p < 0.05), manual muscle testing (ρ = -0.66, p < 0.01), and skeletal muscle endurance as measured by the functional index-2 test (shoulder flexion ρ = -0.62, p < 0.01; hip flexion ρ = -0.65, p < 0.0; heel lift ρ = -0.67, p < 0.01; and toe lift ρ = -0.68, p < 0.01). The ACR-FS is a simple measure of disability that can be used in chart abstraction studies involving IIM patients. We have demonstrated that ACR-FS correlates well with muscle performance tests of strength and endurance.