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

Arch Phys Med Rehabil. 2016 Nov;97(11):1887-1894.e1. doi: 10.1016/j.apmr.2016.04.019. Epub 2016 May 24.


Objectives: (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).

Design: Cross-sectional study.

Setting: MS-specialized outpatient facility.

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

Interventions: 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).

Results: 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%.

Conclusions: 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.

Keywords: Fatigue; Multiple Sclerosis; Rehabilitation; Surveys and questionnaires.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Circadian Rhythm
  • Cross-Sectional Studies
  • Disability Evaluation
  • Fatigue / epidemiology*
  • Fatigue / physiopathology*
  • Fatigue / psychology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Multiple Sclerosis / epidemiology*
  • Multiple Sclerosis / psychology
  • Perception
  • Physical Therapy Modalities*
  • Regression Analysis
  • Reproducibility of Results
  • Self Report
  • Severity of Illness Index
  • Surveys and Questionnaires / standards*

Associated data

  • ISRCTN/ISRCTN69520623
  • ISRCTN/ISRCTN58583714
  • ISRCTN/ISRCTN82353628