Vitamin D deficiency in rheumatoid arthritis prevalence and association with disease activity in Western Saudi Arabia

ABSTRACT

To estimate the prevalence of low serum vitamin D level [25[OH]D] in patients with rheumatoid arthritis [RA] compared with healthy controls, and to analyze the association between 25[OH]D and disease activity. This retrospective analysis included 100 RA patients [85% women] and 100 controls, not on vitamin D supplements from January 2010 to December 2011 at a tertiary care center at the Department of Internal Medicine, King Abdulaziz University Hospital [KAUH], Jeddah, Kingdom of Saudi Arabia. Disease activity was measured using the disease activity score index [DAS28]. According to the DAS28 score, RA patients were divided into 3 groups as high, moderate, and low disease activity. Patients' serum 25[OH]D was measured in a centralized laboratory. The mean 25[OH]D in patients with RA was similar to the control group [32.3 +/- 14.4nmol/L] versus [31.4 +/- 16.4nmol/L] [p=0.41]. Patients with high disease activity had the lowest 25[OH]D levels [18.25 +/- 8.3nmol/L] compared with patients with moderate [35.13 +/- 15.2nmol/L] and low [38.05 +/- 7.3nmol/L] disease activity [p<0.001]. Serum 25[OH]D was negatively correlated with DAS28, which was statistically significant [r= -0.42, p<0.0001]. Serum vitamin D levels in RA patients were similar to the healthy control group. However, significantly lower 25[OH]D values were found in patients who are poorly responding to treatment, and not in a state of disease remission.