25(OH)D Level in Patients with Polyarticular Form of Rheumatoid Arthritis and its Dependence on Certain Clinically Significant Parameters

Introduction. Vitamin D has multiple physiological functions in the human organism and is associated with the pathogenesis of several autoimmune diseases including rheumatoid arthritis. The aim of the study was to evaluate the the level of 25(OH)D in the serum of patients with polyarticular form of rheumatoid arthritis and its dependence on certain clinically significant parameters. Materials and research methods. The study included 93 patients with rheumatoid arthritis, 74.2 % were women. Mean age of women was 53.45 ± 11.16 and of men – 53.29 ±12.06 yrs old. Mean duration of the disease was 8.59 ± 5.99 yrs. Subjects suffering from liver and kidney insufficiency and those who had received vitamin D in the previous 3 months have been excluded. Disease activity was assessed by DAS-28, joint pain degree, morning stiffness time and laboratory measures including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP). 25(OH)D level was evaluated by electrochemiluminescence method. The level of 25(OH)D in serum was evaluated depending on some clinically important parameters: duration of rheumatoid arthritis, clinical signs of the disease, presence or absence of rheumatoid factor in serum (seropositive/seronegative rheumatoid arthritis), some other laboratory parameters of the activity of the process [ESR, CRP, antibodies to cyclic citrullinated peptide (A-CCP)], the degree of activity, functional failure of the joints, Rtg-stage, presence or absence of complications, the dose of methylprednisolone, methotrexate, which were received by patients. Results of the investigation and their discussion. In patients with rheumatoid arthritis the frequency of vitamin D decrease was 92.4 %. The level of 25(OH)D was significantly associated with DAS-28 (r = -0.36, p = 0.001), including the amount of the injured joints (r = -0.36, p < 0.001), ESR level (r = -0.26, p < 0.05), CRP level (r = -0.24, p < 0.05). The mean level of 25(OH)D in serum is significantly lower in patients with rheumatoid arthritis of maximum degree activity, compared with those in whom the disease has minimal activity (16.6 ± 9.3 vs 22.6 ± 9.7 ng/ml). The risk of high disease activity is in patients with vitamin D level less than 20.0 ng/ml: RR = 3.00 (95.0 % CI; 1.01-8.86, p < 0.05). Conclusions. In patients with rheumatoid arthritis the level of vitamin D was decreased in majority of the patients. The level of 25(OH)D was significantly associated with DAS-28, including the amount of the injured joints, ESR, CRP level. The mean level of 25(OH)D in serum was significantly lower in patients with rheumatoid arthritis of maximum degree activity, compared with those in whom the disease has minimal activity. The risk of high disease activity was greater in patients with vitamin D level less than 20,0 ng/ml. Vitamin D deficiency can be an important factor in worsening of rheumatoid arthritis. Vitamin D supplementation is needed to be recommended for treatment of the patients with rheumatoid arthritis routinely.