Relationship between endothelial dysfunction and osteoprotegerin, vitamin D, and bone mineral density in patients with rheumatoid arthritis.

Objectives: We aimed to investigate whether the abnormalities in bone mineral density (BMD) that occur in patients with rheumatoid arthritis (RA) are associated with the presence of endothelial dysfunction.
Methods: Cross-sectional study encompassing 216 subjects (111 patients with RA and 105 age- and sex-matched controls) without history of cardiovascular disease. Endothelial function was determined by brachial artery flow-mediated dilatation (FMD) and BMD by dual x-ray absorptiometry (DXA) measurements. Plasma vitamin D and osteoprotegerin serum (OPG) levels were assessed in patients and controls. Multiple regression analysis was performed to study the relationship between BMD with endothelial function, taking into account vitamin D and OPG levels.
Results: After adjusting for traditional cardiovascular risk factors, vitamin D and OPG levels, BMD emerged as an independent factor associated with lower FMD values in controls, but not in patients with RA. Although OPG levels were inversely associated with FMD values in both RA patients and controls after adjusting for BMD, vitamin D showed this relationship only in the controls.
Conclusions: Whilst OPG is associated with endothelial function in RA patients and controls, vitamin D levels and BMD are related to endothelial function in controls but not in patients with RA.