Vitamin D, disease activity and comorbidities in early spondyloarthritis

To assess the vitamin D status in patients presenting inflammatory back pain suggestive of axial spondyloarthritis and to assess the relationship between vitamin D status and disease activity/severity; comorbidities at baseline and during the first two years of follow-up.

DESIR is a prospective, multicentre, observational study. Vitamin D deficiency was defined as <50 nmol/L and severe deficiency less than 25 nmol/L. Clinical variables were collected at each six month interval visits during the two-year follow-up.

A total of 700 patients were analysed. The mean vitamin D was 54.2±28.7 nmol/L. Severe deficiency were observed in 11.7% versus 5% in the DESIR cohort versus the French population respectively. In the DESIR cohort, after adjusting for season and ethnicity, vitamin D deficiency remained significantly associated with presence of radiological sacroiliitis, higher ASDAS score and elevated BASDAI. Such association was also found between vitamin D deficiency and the mean value of disease activity/severity parameters during the two-year follow-up. Otherwise, vitamin D deficiency was significantly associated with the presence of baseline abdominal obesity (OR=1.65 [1.05-2.61], p=0.03), low HDL (OR=1.71 [1.14-2.55], p=0.01) and presence of metabolic syndrome (OR=2.20 [1.04-4.64], p=0.03) at baseline.

We found a higher percentage of patients with severe vitamin D deficiency in early axial spondyloarthritis. Vitamin D deficiency was associated with higher disease activity and severity and presence of metabolic syndrome. Further longitudinal studies are required to evaluate the interest of vitamin D supplementation on the long-term outcome of the disease.