title: The contributions of disease activity, sleep patterns, and depression to fatigue in systemic lupus erythematosus. A proposed model.
abstract: OBJECTIVE
  This study describes lupus fatigue multidimensionally and introduces a multivariate model: Sleep problems and depression, through reciprocal effects on each other, act as mediators through which lupus disease activity increases fatigue.
  
  
  METHODS
  Self-reported sleep patterns, depression, and fatigue were assessed in 48 women with systemic lupus erythematosus (SLE) and 27 women from the general population. Rheumatologists rated current lupus disease activity.
  
  
  RESULTS
  The SLE group reported greater overall fatigue than did the controls. Temporal and affective dimensions of fatigue were more differentiating than sensory or severity dimensions. The SLE group also reported longer sleep latency and total sleep time, but not higher depression. Using 2-stage regression, a form of structural equation modeling, the proposed lupus fatigue model was supported.
  
  
  CONCLUSIONS
  These preliminary results describe fatigue as a multidimensional phenomenon arising out of several contributing factors. They suggest that fatigue treatment strategies should address mediating processes such as sleep and depression, in addition to disease activity.
authors.affiliation: Graduate Center of the City University of New York, NY 10036, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: McKinley
authors.forename: S C
authors.initials: SC
authors.lastname: Ouellette
authors.forename: G H
authors.initials: GH
authors.lastname: Winkel
mesh_terms: D000328:Adult; D003863:Depression / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D018450:Disease Progression; D005221:Fatigue / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D008875:Middle Aged; D008962:Models, Theoretical; D015999:Multivariate Analysis; D012044:Regression Analysis; D012720:Severity of Illness Index; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires