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.
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.
In a retrospective case-control study design, we evaluated 116 patients in a community clinic classified in two groups,
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.
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).
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.