Vitamin D Levels Among Rheumatoid Arthritis Sudanese Patients: Prevalence and Correlation to Disease Activity - A Bicentric Study.

Purpose: To evaluate vitamin D levels among adult Sudanese RA patients and identify its correlation with RA disease activity.

Patients and methods: A bicentric cross-sectional analytical hospital-based study was performed in two Khartoum State Hospitals between October 2019 and January 2020, enrolling 90 Sudanese patients with RA. Serum vitamin D levels were measured with a standard reference level of 30ng/mL-100ng/mL. A detailed interview-based questionnaire was used to collect the patient's information, clinical data and lab results-disease activity was assessed via the DAS-28 score. The data was then analyzed using SPSS v-24.

Results: Vitamin D levels were low in 79 candidates (87.8%), 53 of which (67.1%) showed moderate insufficiency (10-30ng/mL), and 26 candidates (32.9%) had severe deficiency (less than 10 ng/mL). Regarding the disease activity, 57 participants (63.3%) had moderate disease activity (DAS-28=3.2-5.1), and 22 participants (24.4%) had high disease activity (DAS-28 >5.1). A significant negative correlation was reported between high DAS-28 scores and low vitamin D levels with p-value = <0.001 (95% CI: -0.8591 to 0.0015) and r = -0.44.

Conclusion: Most adult Sudanese rheumatoid arthritis patients showed low vitamin D levels (87.8%), which was also significantly correlated with increased disease activity (P-value <0.05). Moreover, the prevalence of low vitamin D levels was significantly higher than in numerous countries worldwide.