What's in a name? That which we call Multiple Sclerosis Fatigue

A retrospective claims analysis of fatigue in patients with multiple sclerosis on disease-modifying therapy

BACKGROUND

Fatigue, one of the most common symptoms in patients with multiple sclerosis (MS), severely impairs quality of life and the ability to work or perform activities of daily living. Real-world data on fatigue in MS can help inform healthcare decisions and identify care gaps. We identified fatigue in patients with MS, using existing codes for fatigue and proxies of fatigue in healthcare claims database records and characterized cohorts with and without markers of fatigue who had been prescribed disease-modifying therapies for MS (MS-DMTs).

METHODS

In this cohort study, we retrospectively analyzed Optum's de-identified Clinformatics® Data Mart database from 1 January 2015 to 31 December 2019. The index date was defined as the first prescription record date for any MS-DMT during the study identification period. Included patient records were from adults (≥18 years) with ≥2 MS diagnosis claims listed within 12 months prior to the index date. Patients had ≥1 claim for any MS-DMT during the identification period (1 January 2016-31 December 2018), continuous enrollment in a health plan with medical and pharmacy benefits for 12 months before the index date (assessment one), and 12 months following the index date or to end of data availability (assessment two). After exploratory analyses, we applied the following definition to sort patient records into two cohorts according to presence or absence of markers of fatigue: ≥1 diagnosis (International Classification of Diseases, Ninth/Tenth Revisions code) claim for fatigue or ≥2 claims for stimulant drugs or ≥2 procedure claims for a sleep study or ≥2 pharmacy claims for sleep aid drugs; we used the broadest definition of fatigue so meeting any of these criteria qualified patients with MS as having fatigue. To minimize assessment one differences in selected patient characteristics between cohorts, we applied 1:1 propensity score matching with age, sex, US geographic region, and Charlson Comorbidity Index score as covariates. We analyzed demographic data, markers of fatigue, comorbidities at assessment one, and physical disabilities and neurologic impairment at assessment two.

RESULTS

Of 4077 patient records that met the eligibility criteria, 1976 had markers of fatigue. The propensity score-matched cohorts included 1519 patients each with and without fatigue. Assessment one comorbidities including anxiety (25.3% vs 10.5%; P<0.0001), arthritis (17.6% vs 12.9%; P = 0.0003), depression (15.0% vs 3.5%; P<0.0001), and gastrointestinal disorders (20.3% vs 14.2%; P<0.0001) were significantly more prevalent in the cohort with markers of fatigue at assessment one compared with those without fatigue. At assessment two, the cohort with baseline fatigue upon initial assessment was more likely to have indication of physical impairments (spasticity [63.5% vs 35.8%; P<0.0001], bladder dysfunction [37.8% vs 24.0%; P<0.0001], cognitive/behavioral dysfunction [27.0% vs 18.6%; P<0.0001]), neurologic impairments (pain [59.1% vs 44.0%; P<0.0001], depression [29.2% vs 9.9%; P<0.0001], and sensory disturbances [54.2% vs 36.7%; P<0.0001]), compared with the cohort without markers of fatigue at assessment one.

CONCLUSIONS

In our analysis, patients with MS and fatigue were more likely to have comorbidities at assessment one and to develop physical disabilities and neurologic impairments at assessment two. Appropriate identification of patients with MS and fatigue may facilitate targeted care interventions to a group of patients at higher risk for disease progression and disability.

Exercise therapy for fatigue in multiple sclerosis

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

The pathophysiology of motor fatigue and fatigability in multiple sclerosis

Multiple Sclerosis (MS) is a heterogeneous immune mediated disease of the central nervous system (CNS). Fatigue is one of the most common and disabling symptom of MS. It interferes with daily activities on the level of cognition and motor endurance. Motor fatigue can either result from lesions in cortical networks or motor pathways (“primary fatigue”) or it may be a consequence of detraining with subsequent adaptions of muscle and autonomic function. Programmed exercise interventions are used frequently to increase physical fitness in MS-patients. Studies investigating the effects of training on aerobic capacity, objective endurance and perceived fatigability have yielded heterogenous results, most likely due to the heterogeneity of interventions and patients, but probably also due to the non-uniform pathophysiology of fatigability among MS-patients. The aim of this review is to summarize the current knowledge on the pathophysiology of motor fatigability with special reference to the basic exercise physiology that underlies our understanding of both pathogenesis and treatment interventions.

Validation of two new scales for the assessment of fatigue in Multiple Sclerosis: F-2-MS and FACIT-F

BACKGROUND

Fatigue is one of the most common symptoms in neurology, especially in MS patients with a prevalence of 65%. It is described as the most disabling symptom by 40% of MS patients. This study aimed to validate the Functional Assessment of Chronic Illness Therapy fatigue version (FACIT-F) and the F-2-MS scale, a new tool to distinguish between fatigue and fatigability.

METHODS

One hundred and fifteen patients with relapsing-remitting MS were enrolled. All patients completed a comprehensive neuropsychological battery, previously validated in MS. Fatigue was evaluated using the Fatigue Severity Scale (FSS), the Modified version of the Fatigue Impact Scale (MFIS), the Functional Assessment of Chronic Illness Therapy measure system (fatigue version) (FCIT-F), and a new tool for the assessment of fatigue and fatigability: the F-2-MS scale. Internal consistency was estimated with Cronbach's Alpha. For intergroup comparisons, Student's t-test and Pearson's chi-squared test were used. Pearson's correlation test was calculated for quantitative variables. Cohen's d was calculated to evaluate the effect size. Binary logistic regression was performed, considering the presence of fatigue as a criterion variable, and the FACIT-F and F-2-MS scores were added as predictor variables. ROC curves were also estimated. We conducted a confirmatory factor analysis for the F-2-MS scale, considering two latent factors.

RESULTS

FACIT-F and F-2-MS showed high internal consistency. Both scales were highly correlated with MFIS and FSS, and showed a low correlation with Symbol Digit Modalities Test. There were significant differences between fatigued and non-fatigued patients on FACIT-F and F-2-MS scores with large effect sizes. Both scales showed AUC > 0.90 and achieved a correct classification >87%. Confirmatory factor analysis showed moderate evidence of two dimensions on the F-2-MS scale.

CONCLUSIONS

The FACIT-F and F-2-MS scales showed appropriated psychometric properties to be used as fatigue measures in clinical and research settings, allowing a correct distinction between patients with and without fatigue, and contributing to the understanding of the complexities of fatigue in MS.

Distinguishing between Fatigue and Fatigability in Multiple Sclerosis

Fatigue is one of the most common debilitating symptoms reported by persons with multiple sclerosis (MS). It reflects feelings of tiredness, lack of energy, low motivation, and difficulty in concentrating. It can be measured at a specific instant in time as a perception that arises from interoceptive networks involved in the regulation of homeostasis. Such ratings indicate the state level of fatigue and likely reflect an inability to correct deviations from a balanced homeostatic state. In contrast, the trait level of fatigue is quantified in terms of work capacity (fatigability), which can be either estimated (perceived fatigability) or measured (objective fatigability). Clinically, fatigue is most often quantified with questionnaires that require respondents to estimate their past capacity to perform several cognitive, physical, and psychosocial tasks. These retrospective estimates provide a measure of perceived fatigability. In contrast, the change in an outcome variable during the actual performance of a task provides an objective measure of fatigability. Perceived and objective fatigability do not assess the same underlying construct. Persons with MS who report elevated trait levels of fatigue exhibit deficits in interoceptive networks (insula and dorsal anterior cingulate cortex), including increased functional connectivity during challenging tasks. The state and trait levels of fatigue reported by an individual can be modulated by reward and pain pathways. Understanding the distinction between fatigue and fatigability is critical for the development of effective strategies to reduce the burden of the symptom for individuals with MS.

Personalizing Medicine and Technologies to Address the Experiences and Needs of People with Multiple Sclerosis

There is enormous variation in the manifestations of disease experienced by people with multiple sclerosis (PwMS). While this variation makes personalized medicine an attractive goal, there are many challenges to be overcome before this opportunity can be realized. Personalized medicine often focuses on targeted therapies and detailed monitoring, but we also need to recognize that there will be variation in acceptance of these approaches by different PwMS. In other words, deep personalization of medicine will encompass targeted therapy, precision monitoring, tailored to variation in personal attitudes to these transformations in health care. In order to meet the promise of personalized medicine for MS, understanding the experiences of PwMS is necessary both to aid in the uptake of personalized medicine, and to ensure that personalized approaches to monitoring disease and treatment provide a net benefit to PwMS rather than placing additional burdens and stressors on them. Here, we describe recent research that identified five experiential themes for PwMS, and then interpret these themes according to the foundations of personalized medicine to provide a road map for implementation of personalized medicine solutions for PwMS.