Associations of Vitamin D Levels and Vitamin D Receptor Genotypes with Patient-Reported Outcome/Disease Activity in Patients with Rheumatoid Arthritis.

BACKGROUND: The aim of this study is to evaluate the prevalence of vitamin-D insufficiency and vitamin-D receptor (VDR) polymorphisms in rheumatoid arthritis (RA) patients and its association with disease activity and patient reported outcomes (PROs). METHODS: Eighty-two individuals were included in a cross-sectional study (41 RA patients, 41 controls). Prior to assessment, each patient completed a PRO questionnaire. Serum vitamin-D levels and genotyping for VDR were assessed. Vitamin-D deficient patients received vitamin-D supplementation. Re-assessment of disease activity (DAS28) was performed after 9-months. RESULTS: Low vitamin-D levels were more frequent in RA patients (p < 0.01). A negative, but insignificant, association with DAS-28 score was identified; whereas, there was a significant negative association with the PROs (p < 0.01). Vitamin-D supplementation was associated with significant improvement in the patients' scores for pain, fatigue, global assessment, physical disability, and quality of life. In contrast to the control group, the frequency of the recessive TaqI and FokI genotypes was higher in RA patients. CONCLUSIONS: In RA patients, serum vitamin-D level was significantly and inversely associated with both PROs and disease activity. The TaqI and FokI fragment length polymorphisms of VDR significantly contributed to the risk of RA. Having a significant positive impact on patient reported outcomes, vitamin-D supplementation may have a role in RA management.