The co-existence of high prevalence of vitamin D inadequacy among Canadians and high prevalence of systematic autoimmune rheumatic diseases (SARDs) raise the question on relationship between the two situations.
Objective: To determine vitamin D status in known cases of common SARDs and compare to those with non-autoimmune diseases; further, to evaluate the impact of vitamin D on disease activity in rheumatoid arthritis (RA) cases.
Methods: In a retrospective case-control study design, we evaluated 116 patients in a community clinic classified in two groups,
Control group: patients with non-rheumatic disease (n = 56), and Case group: those with rheumatic diseases (n = 60). We compared plasma vitamin D status (25(OH)D), indicators of disease activity and other potential confounders. Further, we determined factors associated with disease activity in RA cases.
Results: The plasma 25(OH)D was significantly lower in Case group (64.8 ± 29.8) compared to CONTROL GROUP (86.8 ± 37.7). High number of SARDs outpatients 56%) had considerably low plasma 25(OH)D concentration. RA cases with low plasma 25(OH)D had over five times higher risk of disease activity (OR = 5.15 95% CI 1.16, 22.9; p = 0.031).
Conclusion: Inadequate vitamin D status in SARDs cases, along with considerably strong association with disease activity in RA cases, indicate the need for proper evaluation of vitamin D status in this clinical population. Moreover, appropriate training should be given to the patients to ensure the intake of the recommended amount of vitamin D per day through diet or supplement.