Original research| Volume 97, ISSUE 11, P1887-1894.e1, November 2016

Real-Time Assessment of Fatigue in Patients With Multiple Sclerosis: How Does It Relate to Commonly Used Self-Report Fatigue Questionnaires?


      • Most patients with multiple sclerosis experience high levels of fatigue throughout the day, or low levels of fatigue in the morning and high levels of fatigue in the afternoon; a minority of patients show high levels of fatigue in the morning and low levels of fatigue in the afternoon, or low levels of fatigue throughout the day.
      • There is a poor agreement between the level of fatigue assessed in real time and fatigue assessed using conventional recall fatigue questionnaires.
      • An important factor that may explain the poor agreement is the feeling of sleepiness; this may indicate that in real time, the level of fatigue is associated with the feeling of sleepiness, and not captured within the conventional recall fatigue questionnaires.



      (1) To assess real-time patterns of fatigue; (2) to assess the association between a real-time fatigue score and 3 commonly used questionnaires (Checklist Individual Strength [CIS] fatigue subscale, Modified Fatigue Impact Scale (MFIS), and Fatigue Severity Scale [FSS]); and (3) to establish factors that confound the association between the real-time fatigue score and the conventional fatigue questionnaires in patients with multiple sclerosis (MS).


      Cross-sectional study.


      MS-specialized outpatient facility.


      Ambulant patients with MS (N=165) experiencing severe self-reported fatigue.


      Not applicable.

      Main Outcome Measures

      A real-time fatigue score was assessed by sending participants 4 text messages on a particular day (How fatigued do you feel at this moment?; score range, 0–10). Latent class growth mixed modeling was used to determine diurnal patterns of fatigue. Regression analyses were used to assess the association between the mean real-time fatigue score and the CIS fatigue subscale, MFIS, and FSS. Significant associations were tested for candidate confounders (eg, disease severity, work status, sleepiness).


      Four significantly different fatigue profiles were identified by the real-time fatigue score, namely a stable high (n=79), increasing (n=57), stable low (n=16), and decreasing (n=13). The conventional questionnaires correlated poorly (r<.300) with the real-time fatigue score. The Epworth Sleepiness Scale significantly reduced the regression coefficient between the real-time fatigue score and conventional questionnaires, ranging from 15.4% to 35%.


      Perceived fatigue showed 4 different diurnal patterns in patients with MS. Severity of sleepiness is an important confounder to take into account in the assessment of fatigue.


      List of abbreviations:

      CIS (Checklist Individual Strength), ESS (Epworth Sleepiness Scale), FSS (Fatigue Severity Scale), MFIS (Modified Fatigue Impact Scale), MS (multiple sclerosis), TREFAMS-ACE (Treating Fatigue in Multiple Sclerosis – Aerobic training, Cognitive behavioral therapy, Energy conservation management)
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