Objective: To investigate 25-OH vitamin D concentrations in 2 independent systemic sclerosis (SSc) populations from France and Italy.
Methods: We studied 156 consecutive SSc patients comparable for demographic characteristics: 90 from Northern France and 66 from Southern Italy. 25-OH vitamin D, intact parathyroid hormone, and serum total calcium and phosphorus were measured in all patients. Vitamin D concentrations < 30 ng/ml were considered insufficiency, while values < 10 ng/ml were classified as deficiency.
Results: Vitamin D insufficiency and deficiency rates were very high and comparable between the 2 populations: 74/90 (82%) versus 57/66 (86%) for insufficiency and 29/90 (32%) versus 15/66 (23%) for deficiency, respectively, in the French and Italian patients. They were not influenced by vitamin D supplementation, which was not statistically different in the 2 groups. In the combined populations, a significant negative correlation was found between low vitamin D levels and European Disease Activity Score (p = 0.04, r = -0.17) and an even more significant correlation was found with acute-phase reactants (p = 0.004, r = -0.23 for erythrocyte sedimentation rate), and low levels of vitamin D were associated with the systolic pulmonary artery pressure (sPAP) estimated by echocardiography (p = 0.004). In multivariate analysis, vitamin D deficiency was associated with sPAP (p = 0.02).
Conclusion: Vitamin D deficiency was very common in the 2 SSc populations, independent of geographic origin and vitamin D supplementation. This suggests that common vitamin D supplementation does not correct the deficiency in SSc patients, and that a higher dose is probably needed, especially in those with high inflammatory activity or severe disease.