title: Fatigue severity remains stable over time and independently associated with orthostatic symptoms in chronic fatigue syndrome: a longitudinal study.
abstract: OBJECTIVE
  to examine fatigue variability over time in chronic fatigue syndrome (CFS) and the effect of other symptoms on its predictability.
  
  
  METHODS
  longitudinal cohort study of patients with CFS (Fukuda criteria).
  
  
  METHODS
  specialist CFS clinical service.
  
  
  METHODS
  phase 1: 100 patients who participated in a study of CFS symptoms in 2005 were revisited in 2009. Phase 2: 25 patients completed fatigue diaries to address intra- and inter-day variability in perceived fatigue.
  
  
  METHODS
  phase 1: subjects completed fatigue impact scale (FIS), Epworth sleepiness scale (ESS), orthostatic grading scale (OGS) and hospital anxiety and depression scale (HADS). Changes in variables represented the differences between 2005 and 2009. Phase 2: subjects rated fatigue on a scale of 0 (no fatigue) to 10 (severe fatigue) four times a day for 5 weeks.
  
  
  RESULTS
  symptom assessment tools were available in both 2005 and 2009 for 74% of patients. FIS and HADS depression (HAD-D) and anxiety (HAD-A) scores significantly improved during follow-up whereas ESS and OGS remained stable. FIS improved in 29/74 (39%) subjects, and by ≥ 10 points in 19 (26%). FIS worsened by ≥ 10 points in 33/74 (45%) subjects. On multivariate analysis, independent predictors of current fatigue (FIS in 2009) were FIS in 2005, HAD-D in 2009, OGS in 2009 and change in HAD-A. Reported fatigue was stable from week to week and from day to day. Patients reported higher fatigue in the morning (mean ± SD; 6.4 ± 2), becoming significantly lower at lunchtime (6.2 ± 2; P < 0.05) and increasing again to 7 ± 2 at bedtime.
  
  
  CONCLUSIONS
  current fatigue is independently associated with current autonomic symptom burden, current depression and change in anxiety during follow-up. These findings have implications for targeted symptom management in CFS.
authors.affiliation: UK NIHR Biomedical Centre in Ageing, Institute of Cellular Medicine, Institute for Ageing and Health, Newcastle University, Newcastle, UK.
authors.forename: D E J
authors.initials: DE
authors.lastname: Jones
authors.forename: J
authors.initials: J
authors.lastname: Gray
authors.forename: J
authors.initials: J
authors.lastname: Frith
authors.forename: J L
authors.initials: JL
authors.lastname: Newton
mesh_terms: D000328:Adult; D000368:Aged; D001008:Anxiety Disorders / Q000209:etiology; D003866:Depressive Disorder / Q000209:etiology; D004812:Epidemiologic Methods; D015673:Fatigue Syndrome, Chronic / Q000150:complications* / Q000523:psychology; D006801:Humans; D008875:Middle Aged; D054971:Orthostatic Intolerance / Q000209:etiology*; D011379:Prognosis