title: Fatigue, patient reported outcomes, and objective measurement of physical activity in systemic lupus erythematosus.
abstract: OBJECTIVE
  Fatigue is a common symptom in systemic lupus erythematosus (SLE), and engaging in physical activity may reduce fatigue. We aimed to characterize relationships between fatigue, other health status measures assessed with the Patient Reported Outcomes Measurement Information System (PROMIS) instruments, and accelerometer-based physical activity measurements in patients with SLE. The internal consistency of each PROMIS measure in our SLE sample was also evaluated.
  
  
  METHODS
  This cross-sectional study analyzed 123 adults with SLE. The primary fatigue outcome was Fatigue Severity Scale score. Secondary outcomes were PROMIS standardized T-scores in seven health status domains. Accelerometers were worn for seven days, and mean daily minutes of light, moderate/vigorous, and bouted (10 minutes) moderate/vigorous physical activity were estimated. Cronbach's alpha was determined for each PROMIS measure to assess internal consistency. Relationships between Fatigue Severity Scale, PROMIS, and physical activity were summarized with Spearman partial correlation coefficients (r), adjusted for average daily accelerometer wear time.
  
  
  RESULTS
  Mean Fatigue Severity Scale score (4.3, SD 1.6) was consistent with clinically relevant levels of fatigue. Greater daily and bouted moderate/vigorous physical activity minutes correlated with lower Mean Fatigue Severity Scale score (r = -0.20, p = 0.03 and r = -0.30, p = 0.0007, respectively). For PROMIS, bouted moderate/vigorous physical activity minutes correlated with less fatigue (r = -0.20, p = 0.03). PROMIS internal consistency was excellent, with Cronbach's alpha > 0.90 for each domain. Mean PROMIS T-scores for fatigue, pain interference, anxiety, sleep disturbance, sleep-related impairment, and physical function were worse than reported for the general US population. More moderate/vigorous physical activity minutes were associated with less pain interference (r = -0.22, p = 0.01). Both light physical activity and moderate/vigorous physical activity minutes correlated with better physical function (r = 0.19, p = 0.04 and r = 0.25, p = 0.006, respectively).
  
  
  CONCLUSIONS
  More time spent in moderate/vigorous physical activity was associated with less fatigue (Fatigue Severity Scale and PROMIS), less pain interference, and better physical function (PROMIS). PROMIS had excellent internal consistency in our SLE sample, and six of seven PROMIS measures indicated poorer average health status in SLE patients compared with the general US population.
authors: Division of Rheumatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA mary-mahieu@fsm.northwestern.edu.
authors: M A
authors: MA
authors: Mahieu
authors: Division of Rheumatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Arthritis and Rheumatism Associates, Wheaton, MD, USA.
authors: G E
authors: GE
authors: Ahn
authors: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: J S
authors: JS
authors: Chmiel
authors: Division of Rheumatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Center for Healthcare Studies, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: D D
authors: DD
authors: Dunlop
authors: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: I B
authors: IB
authors: Helenowski
authors: Department of Adult Health and Gerontological Nursing, Rush University College of Nursing, Chicago, IL, USA.
authors: P
authors: P
authors: Semanik
authors: Center for Healthcare Studies, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: J
authors: J
authors: Song
authors: Department of Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: S
authors: S
authors: Yount
authors: Division of Rheumatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Center for Healthcare Studies, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: R W
authors: RW
authors: Chang
authors: Division of Rheumatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors: R
authors: R
authors: Ramsey-Goldman
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D015444:Exercise; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006304:Health Status; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000503:physiopathology* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D000071066:Patient Reported Outcome Measures; D011788:Quality of Life
keywords: Systemic lupus erythematosus; fatigue; patient-reported outcomes; physical activity