Fatigue measurement scales

It does beg the question: How do you best measure subjective symptoms? It would seem wrong to not measure them at all, because they are important indicators of health, but by the same token it is wrong to measure anything wildly inaccurately, especially when people's lives, in one sense or other, depend on reasonable accuracy.

It feels like people need to take a big step back and and look at the overall problem with a fresh perspective. Not just how to measure, but what are the objectives? How do you deal with trying to measure something that has no clear baseline reference point, far from it often? It feels like discussion of fatigue tinkers around the edges of a much bigger and wider discussion that is needed.

 

https://journals.sagepub.com/doi/10.1177/1352458520941481

The problems of inaccurate terminology

The much-identified impasse in defining daily onset MS-related tiredness appears—in the absence of an accurate label—to derive from the appropriation of the inaccurate nomenclature “fatigue.” In both current medical and colloquial usage, the word fatigue maintains much of the original meaningfulness of its French (15c.) and Latin roots; that is, tiredness which occurs after engaging in some type of activity (Fr.: fatigue, “that which causes weariness” and fatiguer, “to tire”; Latin: fatigare “to weary, to tire out”).

Clinical specifications often draw upon this fatigue nomenclature, suggesting a causal link between activity type and fatigue type (e.g. motor fatigue is caused by excessive physical activity and cognitive/mental fatigue is caused by undertaking an excessive amount of cognitively based tasks).

Along these lines, recent review articles highlight the challenges of definition and assessment of “MS fatigue,” proposing new taxonomies and frameworks for diagnosing and treating “MS fatigue,”14 and addressing the difficulty in distinguishing motor fatigue, tiredness, cognitive fatigue, central fatigue, performance fatigability and perceived fatigability, and the interactions thereof.15 However, in the case of daily onset MS symptoms, there are ample data (indeed, dating back to the early 1800s) showing that the type of activity in which a patient engages does not necessarily reflect the type of impairment a patient experiences (e.g. cognitive activity may be followed by difficulty walking and socioemotional engagement may be followed by feelings of excessive tiredness).3,4,1

By preventing creation of objective measurement strategies, misunderstanding over what constitutes daily onset MS tiredness stymies all attempts at clinical trials of potential therapies, despite ample reports from clinicians and MS patients that the medications amantadine hydrochloride and modafinil as well as the vitamin-D supplement 1-hydroxycholecalciferol and the disease-modifying agent natalizumab have positive effects on daily onset tiredness.21,22

One of the first to directly note the significant difference between “fatigue” in chronic fatigue syndrome (CFS) and “fatigue” in systemic inflammatory diseases, Giovannoni explicates: “Uncertainties over the definition, pathogenesis, and measurement of MS-related fatigue are clearly hampering the testing of specific therapeutic anti-fatigue strategies.”23 For example, one of the few pharmaceutical intervention trials investigating “MS fatigue” as the dependent variable reports positive results for modafinil, but the researchers caution: “..treatments cannot be appropriately evaluated until the clinically relevant variable being studied has been clearly defined.”24 In turn, this constrains the European Medicines Agency (EMA) and U.S. Food and Drug Administration (FDA) from assigning an indication for treatment of daily onset MS tiredness.

 

Not sure this is worth a new thread.

Clinimetrics: Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue), 2023, Ilsley and Howden

Commentary
Strengths of the FACIT-Fatigue include its brevity and ease of administration. Validation of the FACIT-Fatigue across multiple chronic illnesses and multiple languages enhances its applicability for both research and clinical practice. The structure of the FACIT-Fatigue means that it can be completed by patients with or without fatigue, making it a useful screening tool. Normative data are available, with two population-based studies reporting similar mean FACIT scores of 43.5 ± 8.3 and 43.6 ± 9.4.8,16 Validation across different patient populations allows for comparison of fatigue across diagnostic groups.

Open access, https://www.sciencedirect.com/science/article/pii/S1836955323000334