Systematic review of association between vitamin D levels and susceptibility and disease activity of ankylosing spondylitis.
OBJECTIVE
Vitamin D appears to have significant effects on both innate and acquired immunity and deficiency may be associated with both susceptibility and disease severity in some autoimmune conditions. There has been little focus on the potential immunomodulatory role of vitamin D in AS. This study systematically reviews the evidence for an association between vitamin D deficiency and disease susceptibility and severity in AS.


METHODS
A systematic review was conducted using Medline, EMBASE, Web of Science and conference abstracts of the European League Against Rheumatism (2002-13), British Society for Rheumatology (1993-2013) and ACR (2006-13).


RESULTS
Fifteen original articles and five conference abstracts met the criteria for inclusion. All were cross-sectional in design. Seven of 11 studies identified lower concentrations of 25-hydroxyvitamin D (25OHD) in AS patients compared with healthy controls. A significant inverse correlation between 25OHD and disease activity was observed in 5 of 11 studies. The majority of studies that failed to demonstrate significant findings used inappropriate statistical methods.


CONCLUSIONS
Cross-sectional studies using appropriate statistical analyses have highlighted that AS is associated with lower vitamin D concentrations. Within groups of AS patients there is some evidence that low vitamin D concentrations are associated with higher disease activity. However, there are insufficient published data to support an immunomodulatory role for vitamin D in AS. Further study with a longitudinal design is required to understand whether optimizing vitamin D in AS has potential as a disease-modifying intervention.
Department of Rheumatology, Aintree University Hospital and School of Medical Education, University of Liverpool, Liverpool, UK.
Sizheng
S
Zhao
Department of Rheumatology, Aintree University Hospital and School of Medical Education, University of Liverpool, Liverpool, UK.
Stephen J
SJ
Duffield
Department of Rheumatology, Aintree University Hospital and School of Medical Education, University of Liverpool, Liverpool, UK.
Robert J
RJ
Moots
Department of Rheumatology, Aintree University Hospital and School of Medical Education, University of Liverpool, Liverpool, UK. ngoodson@liverpool.ac.uk.
Nicola J
NJ
Goodson
D003430:Cross-Sectional Studies; D004198:Disease Susceptibility; D006801:Humans; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000209:etiology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D
1; 25-dihydroxyvitamin D; 25-hydoxyvitamin D; ankylosing spondylitis; anti-TNF; axial spondyloarthritis; cross-sectional; disease activity; vitamin D