Relationship between Vitamin D levels and pain and disease activity in patients with newly diagnosed axial spondyloarthritis

Objectives:To explore the relationship between Vitamin D levels and pain and disease activity in patients with newly diagnosed axial spondyloarthritis(axSpA).Methods:A convenience sample of 131 newly diagnosed axSpA patients and 60 healthy controls was recruited from July 2016 to December 2018.Serum 25-hydroxyvitamin D[25(OH)D]was measured to assess vitamin D levels.Disease activity was assessed by objective indicators[Erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),the Bath Ankylosing Spondylitis Metrology Index(BASMI)],patientreported questionnaires[the Bath Ankylosing Spondylitis Disease Activity Index(BASDAI),and the Bath Ankylosing Spondylitis Functional Index(BASFI)].Pain intensity and interference were also assessed.Results:Vitamin D insufficiency[serum 25(OH)D levels<50 nmol/L]was found in 46(35.1%)and 25(43.3%)of the axSpA patients and the healthy controls,respectively.Female patients had higher risk(0R:4.928;95%CI:1.921-12.642)for vitamin D insufficiency than male patients.Vitamin D was positively correlated with CRP,ESR level,the BASFI,and the BASMI.Logistic regression showed that vitamin D levels were not associated with pain,or disease activity in the newly diagnosed axSpA patients.Gender was the only predictive variable for vitamin D levels.Conclusions:Vitamin D insufficiency was prevalent in both newly diagnosed axSpA patients and healthy controls.There was no association between vitamin D and pain and disease activity in the newly diagnosed axSpA patients.Monitoring vitamin D levels is important and early intervention for vitamin D insufficiency is needed,especially in female patients.