title: Minimal clinically important difference for 7 measures of fatigue in patients with systemic lupus erythematosus.
abstract: OBJECTIVE
  To determine the minimal clinically important difference (MCID) for 7 measures of fatigue in patients with systemic lupus erythematosus (SLE).
  
  
  METHODS
  Study subjects completed 7 fatigue instruments [Fatigue Severity Scale (FSS), Multidimensional Assessment of Fatigue (MAF), Multidimensional Fatigue Inventory (MFI), Vitality scale of the MOS-SF-36, Chalder Fatigue Scale (CFS), Functional Assessment of Chronic Illness Therapy-Fatigue, and a global Rating Scale (RS)] and then participated in a series of interviews with other study participants comparing their fatigue with one another. Each interview participant rated the difference in their fatigue levels on a 7-point transition scale. The MCID was estimated from the mean difference in fatigue scores between each pair of interview participants based on their subjective rating of fatigue contrast. The MCID was also estimated using linear regression modeling.
  
  
  RESULTS
  Eighty patients with SLE participated. Patients reported significant levels of fatigue [mean normalized (0 = none, 100 = maximum) fatigue scores for the 7 instruments ranged from 49.8 (CFS) to 71.1 (FSS)]. The MCID of "a little more" fatigue tended to be greater than the MCID for a "little less fatigue" and differed significantly for FSS and MAF. The MCID of normalized scores estimated by linear regression ranged from 7.0 (CFS) to 14.3 (MFI).
  
  
  CONCLUSIONS
  Fatigue is a common and debilitating component of SLE. Estimates of MCID will help to interpret changes observed in a fatigue score and will be critical in estimating sample size requirements for clinical trials including fatigue as an outcome.
authors.affiliation: Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Ewan C
authors.initials: EC
authors.lastname: Goligher
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouchot
authors.forename: Rollin
authors.initials: R
authors.lastname: Brant
authors.forename: Raheem B
authors.initials: RB
authors.lastname: Kherani
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Aviña-Zubieta
authors.forename: Diane
authors.initials: D
authors.lastname: Lacaille
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Lehman
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ensworth
authors.forename: Jacek
authors.initials: J
authors.lastname: Kopec
authors.forename: John M
authors.initials: JM
authors.lastname: Esdaile
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Liang
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D004185:Disability Evaluation; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires