Association Between Rheumatoid Arthritis and Serum Vitamin D Levels

Introduction Vitamin D is responsible for regulating innate and adaptive immune responses and for boosting the immune system; hence, a decline in its levels results in autoimmunity. Current studies have linked the deficiency of vitamin D to different autoimmune diseases, including rheumatoid arthritis (RA). In this study, we will determine the association between vitamin D level and RA. Methods This is a case-control study, conducted in a tertiary care hospital in Pakistan from January 2021 to May 2021. Three hundred patients with a confirmed recent diagnosis of RA were enrolled as the study group. Another 300 participants without RA, matched for age and gender, were enrolled in the study as a control group. RA was diagnosed on the basis of clinical symptoms, radiological features on X-ray, and anti-citrullinated protein levels of more than 20 u/mL. Results The mean vitamin D level in participants with RA was significantly lower than in the placebo group (30.18 ± 6.27 vs. 38.29 ± 7.98; p-value: <0.0001). The mean vitamin D level in participants with positive RF patients was significantly lower compared to rheumatoid factor (RF)-negative RA patients (29.21 ± 5.16 vs. 32.26 ± 7.02; p-value: <0.0001). There were more participants with hypovitaminosis D in RF-positive participants as compared to RF negative (88.6% vs. 44.3%; p-value: 0.00001). Conclusion There is a high prevalence of vitamin D deficiency in patients with RA and there is a link with disease severity. Therefore, a high index of suspicion is required while evaluating the at-risk patients, especially women, with complaints of vitamin D deficiency. Vitamin D supplementation may be needed for the prevention or avoidance of the progression of the disease.