title: Fatigue and blood pressure in primary Sjogren's syndrome.
abstract: OBJECTIVE
  Primary Sjogren's syndrome (SS) is an autoimmune disease characterized by fatigue. Little is known about the genesis of fatigue. Fatigue is thought to represent a multidimensional concept and it is important to be able to measure it confidently. The aims were to evaluate the reliability and validity of the 20-item Multidimensional Fatigue Inventory (MFI-20) in SS and to search for factors associated with this disabling symptom.
  
  
  METHODS
  Forty-eight women with primary SS completed the MFI-20 questionnaire. The results were compared with age-matched women with fibromyalgia (FM) and healthy controls. Convergent construct validity was assessed by correlations to a Visual Analogue Scale (VAS) for global fatigue by Spearman's correlation (r(s)). Test-retest reliability was analysed by the intraclass correlation coefficient (ICC) in 28 women. Associations between clinical variables and subscales of the MFI-20 were analysed.
  
  
  RESULTS
  The SS women scored significantly higher in all subscales of the MFI-20 compared to controls but similar to FM. The ICCs were satisfactory, ranging from 0.66 for general fatigue to 0.85 for the total score of MFI-20. All subscales correlated significantly to VAS for global fatigue, general fatigue showing the highest correlation (r(s) = 0.70). The estimated number of hours of sleep/day was significantly associated with many of the fatigue dimensions. All five subscales of the MFI-20 were inversely associated with diastolic blood pressure (BP) and two with systolic BP.
  
  
  CONCLUSIONS
  The MFI-20 was found to be a reliable and valid tool for the measurement of fatigue in primary SS. High levels of fatigue were correlated with low BP, suggesting an associated involvement of the autonomic nervous system.
authors.affiliation: Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, Göteborg University, Sweden. helena.forsblad@vgregion.se
authors.forename: H Forsblad
authors.initials: HF
authors.lastname: d'Elia
authors.forename: E
authors.initials: E
authors.lastname: Rehnberg
authors.forename: G
authors.initials: G
authors.lastname: Kvist
authors.forename: A
authors.initials: A
authors.lastname: Ericsson
authors.forename: Yt
authors.initials: Y
authors.lastname: Konttinen
authors.forename: K
authors.initials: K
authors.lastname: Mannerkorpi
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D005356:Fibromyalgia; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012859:Sjogren's Syndrome / Q000503:physiopathology*