Vitamin D Deficiency In Connective Tissue Disease-associated Interstitial Lung Disease

Objectives: To determine and compare the prevalence of vitamin D deficiency in patients with connective tissue disease-associated interstitial lung disease(CTD-ILD).Methods: The level of vitamin D was determined by the serum levels of 1,25(OH)2D3.We evaluated 144 patients in our study,including 53 subjects in the CTD-ILD and 91 subjects in the CTD group without ILD.The diagnosis of CTD and ILD are in accordance with internationally recognized diagnostic criteria.The patients with other known causes of ILD and other pulmonary diseases were excluded.We compared the baseline demographic and laboratory datum in the two groups,Vitamin D deficiency level was <20 ng/ml.This is a retrospective study.Results: Serum vitamin D levels were significantly lower in CTD-ILD patients(p<0.0001).Vitamin D deficiency was lower in the CTD-ILD group(mean±SD: 11.5±4.1 ng/ml)than in the control group(13.9±4.8 ng/ml,p=0.004).Age(p=0.002),history of immunosuppressive therapies(p=0.011),antinuclear antibody(p=0.037),anti-CCP antibody(p= 0.026),serum calcium(p=0.002)also have statistical significance compared with CTD group.As the level of vitamin D decreased,the positive rate of anti-nuclear antibody gradually increased(p=0.045).When the odds ratio was adjusted for CTD-ILD,vitamin D deficiency was risk factor for CTD-ILD,whereas serum levels of calcium was protective factor for CTD-ILD.Conclusions: Serum vitamin D deficiency is associated with CTD-ILD and is a risk factor.Therefore,vitamin D may play a role in the pathogenesis of CTD-ILD.