Factors associated with decreasing serum 25(OH)D among Japanese patients with rheumatoid arthritis: Results from the IORRA cohort study

Abstract

Objective: The aim of this study was to investigate factors that predict a decrease in serum 25(OH)D among Japanese patients with rheumatoid arthritis (RA).

Methods: In 2011 and 2013, serum 25(OH)D was evaluated in the same 2534 Japanese patients with RA (2179 women and 355 men) who participated in the Institute of Rheumatology Rheumatoid Arthritis (IORRA) cohort study. A vitamin D deficiency was defined as serum 25(OH)D levels <20 ng/mL. Predictive factors resulting in decreased serum 25(OH)D over a 2-year period were evaluated using multivariate logistic regression.

Results: The prevalence of vitamin D deficiency was 73.3% in 2011 and 68.2% in 2013. Serum 25(OH)D levels decreased by >5 ng/mL from 2011 to 2013 in 224 (8.8%) patients. A serum 25(OH)D decrease of >5 ng/mL was significantly associated with female gender, younger age, and disuse of bisphosphonates among all patients, and younger age, higher Japanese health assessment questionnaire disability index (JHAQ-DI), increased tender joint counts, and disuse of bisphosphonates and/or active vitamin D₃ among women with RA.

Conclusion: Female gender, younger age, JHAQ-DI, tender joint counts, and disuse of bisphosphonates and/or active vitamin D₃ appear to be associated with a decrease in serum 25(OH)D in Japanese patients with RA.

Keywords:

• Japanese
• osteoporosis
• rheumatoid arthritis
• vitamin D deficiency
• 25(OH)D

Acknowledgements

The authors thank all members of the Institute of Rheumatology, Tokyo Women’s Medical University for the successful management of the IORRA cohort.

Conflict of interest

MN has served on speakers’ bureaus for Bristol-Myers Squibb. TF has served on speakers’ bureaus for Asahi Kasei Pharma Corporation, Bristol-Myers Squibb, Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Ono Pharmaceutical Co., Ltd., Pfizer Japan Inc., Takeda Pharmaceutical Co., Ltd., and UCB Japan Co., Ltd. EI has served on speakers’ bureaus for Merck Serono Co., Ltd. ET has served on speakers’ bureaus for Abbvie, Ayumi Pharmaceutical Co., Ltd., Bristol-Myers Squibb, Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Nippon Kayaku, Pfizer Japan Inc., Takeda Pharmaceutical Co., Ltd., and UCB Japan Co., Ltd. AN has received consulting fees from Nippon-Kayaku and has served on speakers’ bureaus for Bristol-Myers Squibb, Chugai Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Novartis Pharmaceutical K.K., Pfizer Japan Inc., and Siemens. AT has served on speakers’ bureaus for Pfizer Japan Inc. KI has served on speakers’ bureaus for Abbvie, Astellas Pharma Inc., Asahi Kasei Pharma Corporation, Ayumi Pharmaceutical Co., Ltd., Bristol-Myers Squibb, Eisai Co., Ltd., Chugai Pharmaceutical Co., Ltd., Hisamitsu Pharmaceutical Co., Inc., Janssen Pharmaceutical K.K., Kaken Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Taisho Toyama Pharmaceutical Co., Ltd., and Takeda Pharmaceutical Co., Ltd. HY has received a research grant from AbbVie, Astellas Pharma Inc., Ayumi Pharmaceutical Co., Ltd., Bristol-Myers Squibb, Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eisai Co., Ltd., Janssen Pharmaceutical K.K., Kaken Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Corporation, MSD K.K., Nippon Shinyaku Co., Ltd., Ono Pharmaceutical Co., Ltd., Pfizer Japan Inc., Takeda Pharmaceutical Co., Ltd., and UCB Japan Co., Ltd., and has served on speakers’ bureaus for Astellas Pharma Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eisai Co., Ltd., Hoffmann-La Roche, Mitsubishi Tanabe Pharma Corporation, Nippon-Kayaku, Pfizer Japan Inc., Takeda Pharmaceutical Co., Ltd., and YL Biologics Ltd. These sponsors were not involved in the: study design; collection, analysis, and interpretation of data; writing of the paper; and/or decision to submit for publication.