Effect of vitamin D on the recurrence rate of rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease that is characterized by chronic inflammation affecting target tissues including the joints, bones, and synovial membrane. However, the etiology and pathogenesis of RA remains to be determined, and investigations into the treatment of RA are imperative. Vitamin D (Vit D) was previously found to be associated with the activity of RA and exerts therapeutic benefits. The aim of the present study was to investigate the effect of Vit D on the recurrence rate of RA. A total of 377 patients with RA at remission stage were divided into the normal Vit D group and the Vit D-deficient group according to their Vit D levels at baseline. The patients in the Vit D-deficient group were further randomly allocated to receive treatment with or without Vit D. The patients were followed up for 24 months, and the visual analogue scale, as well as the number of pain and swelling joints were recorded every 2-3 months. In addition, C-reactive protein and the blood sedimentation rate were measured every 2-3 months to assess the recurrence of RA based on disease activity score 28 (DAS28). The recurrence rate of RA was 16.7, 19.0 and 29.5% for the normal Vit D group (n=168), Vit D treatment subgroup (n=84), and non-Vit D treatment subgroup (n=88), respectively. The recurrence rate of the normal Vit D group was lower, compared to the non-Vit D treatment subgroup, and the difference was statistically significant. However, the difference was not statistically significant between the Vit D treatment subgroup and non-Vit D treatment subgroup. In conclusion, a decreased level of Vit D is a risk factor for the recurrence of RA.