Background Vitamin D (25[OH]D) deficiency is reported to be common in patients with rheumatoid arthritis (RA). Low vitamin D (25[OH]D) levels are also reported to be associated with disease activity, physical disability, and cardiometabolic intermediates in patients with RA [1-3]. There are limited reports concerning prevalence of and factors associated with vitamin D deficiency in the literature on Japanese patients with RA. Previously, we utilized data from our prospective, observational study of RA in Japan (IORRA, Institute of Rheumatology Rheumatoid Arthritis) to report clinical risk factors for fractures in Japanese patients with RA [4, 5].
Objectives To determine the prevalence of vitamin D deficiency and associations with clinical characteristics in Japanese patients with RA.
Methods Serum 25(OH)D levels, laboratory data, and clinical data were obtained from 4,793 patients with RA (4,075 women, 718 men, mean age 59.7 years) who participated in the IORRA observational cohort study in April and May of 2011. Serum vitamin D levels were evaluated using a radioimmunoassay. We defined vitamin D deficiency as < 20 ng/mL and severe deficiency as < 10 ng/mL Associations of vitamin D deficiency and severe deficiency with patient characteristics were examined using multivariate logistic regression.
Results Among all patients, the mean (SD) serum 25(OH)D level was 16.9 (6.1) ng/mL and the prevalence of vitamin D deficiency and severe deficiency were 71.8% and 11.5%, respectively. In multivariate analysis, female gender, younger age, high Japanese health assessment questionnaire (J-HAQ) disability score, and low serum total cholesterol and high serum alkaline phosphate (ALP) levels were significantly associated with both vitamin D deficiency and severe deficiency (P < 0.01). Low serum total protein levels and non-steroidal anti-inflammatory drug (NSAID) use were significantly correlated with vitamin D deficiency (P < 0.01).
Conclusions Vitamin D deficiency appears to be common in Japanese patients with RA, as previously reported for patients of other ethnicities. Female gender, younger age, high HAQ disability score, low serum levels of total cholesterol and total protein, high serum ALP levels, and NSAID use appear to be associated with vitamin D deficiency in Japanese patients with RA.
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Disclosure of Interest T. Furuya: None Declared, T. Hosoi: None Declared, E. Tanaka: None Declared, A. Nakajima: None Declared, A. Taniguchi: None Declared, S. Momohara: None Declared, H. Yamanaka Grant/research support from: Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Wyeth K.K., Daiichi Sankyo Co., Ltd., Banyu Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Abbott Japan Co., Ltd., Eisai Co., Ltd., Santen Pharmaceutical Co., Ltd., Taishotoyama Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited, Kissei Pharmaceutical Co., Ltd., and Janssen Pharmaceutical K.K., Speakers bureau: Abbott, Eisai Co., Ltd., Takeda Pharmaceutical Company Limited, Mitsubishi Tanabe Pharma Corporation, Janssen Pharmaceutical K.K., Hoffmann-La Roche, and Chugai Pharmaceutical Co., Ltd.