Public Library Science Acta Medica Okayama 1932-6203 17 6 2022 Real-world data on vitamin D supplementation and its impacts in systemic lupus erythematosus: Cross-sectional analysis of a lupus registry of nationwide institutions (LUNA) e0270569 EN Keigo Hayashi Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Ken-Ei Sada Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yosuke Asano Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yu Katayama Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Keiji Ohashi Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Michiko Morishita Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshia Miyawaki Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Haruki Watanabe Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takayuki Katsuyama Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Mariko Narazaki Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshinori Matsumoto Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Nobuyuki Yajima Department of Medicine, Division of Rheumatology, Showa University School of Medicine Ryusuke Yoshimi Department of Stem Cell and Immune Regulation, Yokohama City University Graduate School of Medicine Yasuhiro Shimojima Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine Shigeru Ohno Center for Rheumatic Diseases, Yokohama City University Medical Center Hiroshi Kajiyama Department of Rheumatology and Applied Immunology, Faculty of Medicine, Saitama Medical University Kunihiro Ichinose Department of Immunology and Rheumatology, Advanced Preventive Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences Shuzo Sato Department of Rheumatology, Fukushima Medical University School of Medicine Michio Fujiwara Department of Rheumatology, Yokohama Rosai Hospital Jun Wada Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Background Although vitamin D concentration is reportedly associated with the pathogenesis and pathology of systemic lupus erythematosus (SLE), benefits of vitamin D supplementation in SLE patients have not been elucidated, to our knowledge. We investigated the clinical impacts of vitamin D supplementation in SLE. Methods A cross-sectional analysis was performed using data from a lupus registry of nationwide institutions. We evaluated vitamin D supplementation status associated with diseaserelated Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) as a parameter of long-term disease activity control. Results Of the enrolled 870 patients (mean age: 45 years, mean disease duration: 153 months), 426 (49%) received vitamin D supplementation. Patients with vitamin D supplementation were younger (43.2 vs 47.5 years, P < 0.0001), received higher doses of prednisolone (7.6 vs 6.8 mg/day, P= 0.002), and showed higher estimated glomerular filtration rates (79.3 vs 75.3 mL/min/1.73m(2), P= 0.02) than those without supplementation. Disease-related SDI (0.73 +/- 1.12 vs 0.73 +/- 1.10, P = 0.75), total SDI, and SLE Disease Activity Index (SLEDAI) did not significantly differ between patients receiving and not receiving vitamin D supplementation. Even after excluding 136 patients who were highly recommended vitamin D supplementation (with age >= 75 years, history of bone fracture or avascular necrosis, denosumab use, and end-stage renal failure), disease-related SDI, total SDI, and SLEDAI did not significantly differ between the two groups. Conclusions Even with a possible Vitamin D deficiency and a high risk of bone fractures in SLE patients, only half of our cohort received its supplementation. The effect of vitamin D supplementation for disease activity control was not observed. No potential conflict of interest relevant to this article was reported.