title: Vitamin D deficiency in systemic lupus erythematosus: prevalence, predictors and clinical consequences.
abstract: OBJECTIVE
  We aimed to establish the prevalence, predictors and clinical consequences of vitamin D deficiency in patients with SLE.
  
  
  METHODS
  Cross-sectional study including patients fulfilling ACR criteria for the classification of SLE. Serum 25(OH)D levels at 30 and 10 ng/ml were the cut-off values for vitamin D insufficiency and vitamin D deficiency, respectively. SLE activity was measured by SLEDAI and irreversible organ damage by the SLICC-ACR index. Fatigue was quantified using a 0-10 visual analogue scale (VAS).
  
  
  RESULTS
  Ninety-two patients (90% women, 98% white) were included in the study. Sixty-nine (75%) and 14 (15%) patients presented with vitamin D insufficiency and deficiency, respectively. Female sex (P = 0.001), treatment with HCQ (P = 0.014) and treatment with calcium and vitamin D (P = 0.049) predicted higher levels of 25(OH)D. Photosensitivity [odds ratio (OR) 3.5] and photoprotection (OR 5.7) predicted vitamin D insufficiency and deficiency, respectively. Higher age (OR 0.95) and HCQ use (OR 0.29) protected against vitamin D deficiency. Patients with vitamin D deficiency had a higher degree of fatigue as quantified by a 0-10 VAS (mean 5.32 vs 4.03, P = 0.08). No relation was seen between vitamin D insufficiency or deficiency and disease duration, SLEDAI or SLICC-ACR indexes.
  
  
  CONCLUSIONS
  Vitamin D insufficiency and deficiency are common in patients with SLE and are associated with sun avoidance. HCQ prevented vitamin D deficiency. Vitamin D deficiency was related to a higher degree of fatigue. Vitamin D levels had no relation with SLE severity.
authors.affiliation: Servicio de Medicina Interna, Hospital de Cruces, 48903-Bizkaia, Spain. r.irastorza@euskalnet.net
authors.forename: G
authors.initials: G
authors.lastname: Ruiz-Irastorza
authors.forename: M V
authors.initials: MV
authors.lastname: Egurbide
authors.forename: N
authors.initials: N
authors.lastname: Olivares
authors.forename: A
authors.initials: A
authors.lastname: Martinez-Berriotxoa
authors.forename: C
authors.initials: C
authors.lastname: Aguirre
mesh_terms: D000328:Adult; D000367:Age Factors; D018501:Antirheumatic Agents / Q000627:therapeutic use; D002112:Calcifediol / Q000097:blood; D003430:Cross-Sectional Studies; D005221:Fatigue / Q000209:etiology; D005260:Female; D006801:Humans; D006886:Hydroxychloroquine / Q000627:therapeutic use; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D014808:Vitamin D Deficiency / Q000097:blood / Q000209:etiology*
chemical_list: D018501:Antirheumatic Agents; D006886:Hydroxychloroquine; D002112:Calcifediol