Fatigue, Muscle Strength and Vitamin D Status in Women With Systemic Lupus Erythematosus Compared With Healthy Controls

Lupus. 2012 Mar;21(3):271-8. doi: 10.1177/0961203311425530. Epub 2011 Oct 17.

Abstract

Recent studies have demonstrated an inverse relationship between vitamin D levels and fatigue in systemic lupus erythematosus (SLE). The aims of this study were to evaluate proximal muscle strength, fatigue and vitamin D levels in women with SLE compared with healthy controls and to investigate relationships between these factors in a cohort of women with SLE. Forty-five women (24 SLE, 21 healthy controls) participated. Primary outcome measures were the fatigue severity scale (FSS), isometric muscle strength of dominant limbs using hand held dynamometry, two functional tests--the 30-second chair stand test and the 1-kg arm lift test, with vitamin D status measured using 25(OH)D. Overall 25(OH)D levels were 68.4 (22.4) nmol/L with no difference between SLE and control groups. There was a statistically and clinically significant difference in fatigue, 1-kg arm lift, 30-second sit to stand, knee extension, hip flexion, hip abduction, shoulder flexion and grip strength in the SLE group compared with the control group (p < 0.05). In the SLE group FSS was moderately correlated with both functional measures (1-kg arm lift r = -0.42, 30-second chair stand r = -0.44, p < 0.05). However, no statistically significant correlation between dynamometry measures and fatigue was evident. There was no association between fatigue and 25(OH)D level (r = -0.12). In summary, women with SLE were weaker and demonstrated reduced physical function and higher fatigue levels than healthy controls. Fatigue was related to physical function but not vitamin D status or maximal isometric strength in vitamin D replete individuals with SLE.

MeSH terms

  • Adult
  • Case-Control Studies
  • Cohort Studies
  • Cross-Sectional Studies
  • Fatigue / etiology*
  • Female
  • Humans
  • Lupus Erythematosus, Systemic / physiopathology*
  • Middle Aged
  • Muscle Strength Dynamometer
  • Muscle Strength*
  • Severity of Illness Index
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood

Substances

  • Vitamin D
  • 25-hydroxyvitamin D