title: Correlation between disease activity of pediatric-onset systemic lupus erythematosus and level of vitamin D in Taiwan: A case-cohort study.
abstract: BACKGROUND
  Vitamin D deficiency has been associated with systemic lupus erythematosus (SLE), but there is no consensus on the role of serum vitamin D in evaluating or predicting disease activity. This study aimed to demonstrate the direct correlation between vitamin D level and pediatric-onset SLE disease activity by a retrospective cohort study design.
  
  
  METHODS
  Thirty-five patients with pediatric-onset SLE and paired sera at the active and inactive disease states were enrolled. Disease activity was defined by Systemic Lupus Erythematosus Disease Activity Index 2000, and active lupus nephritis (LN) was defined as active urine sediment, and proteinuria >2+ on stick or >500 mg/day. All data were reviewed and calculated from previous medical records. The levels of both vitamin D2 and vitamin D3 were checked by electrochemiluminescence immunoassay.
  
  
  RESULTS
  Serum 25-hydroxyvitamin D (25-OH D) levels in the active status were significantly lower compared to that in inactive disease status (12.0 ± 7.2 ng/mL vs. 15.4 ± 7.4 ng/mL, p = 0.005). A subgroup analysis revealed that at active disease status, patients with LN had lower 25-OH D levels than patients without LN (16.3 ± 8.2 ng/mL vs. 9.8 ± 5.6 ng/mL, p = 0.023). Moreover, there is a significant inverse correlation between serum 25-OH D levels and Systemic Lupus Erythematosus Disease Activity Index 2000 at both inactive (r = -0.335, p = 0.003) and active (r = -0.373, p = 0.016) disease status.
  
  
  CONCLUSIONS
  Serum vitamin D levels are inversely correlated with SLE disease activity at both active and inactive disease status, and also with the presence of LN at active disease stage.
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Ting-Chun
authors.initials: TC
authors.lastname: Lin
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Jhong-Yong
authors.initials: JY
authors.lastname: Wu
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Microbiology and Immunology, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Ming-Ling
authors.initials: ML
authors.lastname: Kuo
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Liang-Shiou
authors.initials: LS
authors.lastname: Ou
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Yeh
authors.affiliation: Division of Allergy, Asthma and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address: long@adm.cgmh.org.tw.
authors.forename: Jing-Long
authors.initials: JL
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D015897:Comorbidity; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000150:complications* / Q000453:epidemiology; D008181:Lupus Nephritis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013624:Taiwan / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood*; D014808:Vitamin D Deficiency / Q000150:complications* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: cohort study; disease activity; lupus nephritis; pediatric onset; systemic lupus erythematosus; vitamin D deficiency