Vitamin D plays a key role in the regulation of calcium metabolism and bone physiology and also presents immunomodulatory effects. In contrast to healthy individuals, macrophages and synoviocytes synovium of patients with rheumatoid arthritis (RA) have receptors for vitamin D. In vitro, 1,25 Vitamin D inhibits T cell proliferation and cytokine synthesis and decreases pro-inflammatory process. There is an inverse relationship, at least in some epidemiological studies, between the circulating levels of 25OH vitamin D and the occurrence and / or activity of RA. The hypothesis of our study is that natural vitamin D supplementation in patients with RA and a vitamin D deficiency (vitamin D <30 ng / mL) improves functional disability.

This is an interventional, multicenter (13 rheumatology units) randomized, double-blinded study against placebo, lasting 24 weeks. The main objective is to demonstrate that treatment with cholecalciferol improves functional disability (HAQ) in patients with RA not in remission (DAS28 VS> 2.6 and the investigator does not think to change the treatment in the 3 months after enrolment) and vitamin D deficiency (vitamin D <30 ng / ml). Secondary objectives will be to examine whether there is a decrease in disease activity (tender joint count, swollen joint count, VAS, EVA activity, ESR, CRP, EULAR criteria, ACR), a decrease in fatigue (FACIT EVA - fatigue), improved quality of life (SF36, EMIR, PASS, MOS) and the impact of RA (RAID).

Inclusion Criteria:

- Patients with RA (ACR 1987) not in remission (DAS28> 2.6) in whom no change in treatment is considered by the investigator for at least 3 months, DMARD stable RA for at least 3 months and lack of infiltration in the last 2 months

- Serum 25-OH vitamin D <30 ng / ml

Exclusion Criteria:

• Arthritis resulting in class IV functional disability (according to the ACR criteria)
• Hypercalcemia (serum calcium> 2.6 mmol/L) and/or known hypercalciuria (calcium excretion> 4 mg / kg / day), history of renal colic, thiazideic therapy.
• Known hypersensitivity to vitamin D
• Patient refused to sign the consent form, pregnant or nursing women, patients minor, major patients under protection of the Act