Abstract
Background Epidemiological studies indicate that vitamin D deficiency may increase the risk of developing autoimmune and chronic diseases such as rheumatoid arthritis (RA) and, therefore, is prevalent in patients with RA. Additionally, vitamin D insufficiency is associated with significant disease activity in patients with RA. This study aimed to assess the prevalence of vitamin D deficiency in Saudi patients with RA and determine whether there is an association between low vitamin D levels and RA disease activity. Methodology This cross-sectional retrospective study was conducted from October 2022 to November 2022 on patients who attended the rheumatology clinic at King Salman bin Abdulaziz Medical City, Medina, Saudi Arabia. Patients aged ≥18 years, diagnosed with RA, and not on vitamin D supplements were included. Demographic, clinical, and laboratory data were collected. Disease activity was measured using the disease activity score index of a 28-joint count using the erythrocyte sedimentation rate (DAS28-ESR). Results In total, 103 patients were included, with 79 patients being women (76.7%) and 24 being men (23.3%). The vitamin D level ranged from 5.13 to 94 ng/mL, with a median of 24. Of the studied cases, 42.7% had insufficient vitamin D levels, 22.3% had a deficiency, and 15.5% had severe deficiency. There were statistically significant correlations between the median vitamin D level and C-reactive protein (CRP), the number of swollen joints, and DAS. A lower median vitamin D level was detected among cases with positive CRP, swollen joints >5, and higher disease activity. Conclusions Patients with RA in Saudi Arabia were more likely to have low vitamin D levels. Moreover, vitamin D deficiency was linked to disease activity. Therefore, the measurement of vitamin D levels in patients with RA is essential, and vitamin D supplements might be important to improve disease outcomes and prognoses.