Correlation of serum vitamin D levels with disease activity in ankylosing spondylitis

Purpose: The purpose of this study was to assess the correlation of serum vitamin D levels with disease activity in Ankylosing spondylitis patients. Type of Study: Hospital Based Cross Sectional study. Methods: Fifty patients of ankylosing spondylitis and fifty apparently healthy controls were enrolled in study from October 2015 to May 2017. Bath AS Disease Activity Index (BASDAI), erythrocyte sedimentation rate (ESR), C reactive protein, Ankylosing spondylitis disease activity score (ASDAS), Serum 25hydroxyvitamin D (25OHvitD) were assessed in Ankylosing spondylitis patients. Categorical variables were presented in number and percentage (%) and continuous variables were presented as mean ± SD. Pearson`s and spearman`s correlation coefficient were used to analyse relationship between Vitamin D and Disease activity. Results: The patient population studied, had an average age of 31 .23 ± 6.34 (mean ± SD) years (range 18-45 years). In our study in group 1(cases): 37 (74 %) cases had Serum 25-OH Vit D levels < 30 nmol/L i.e. Vitamin D deficiency. Mean serum levels were 23.04 nmol/L ± 14.9. In group 2(controls): 11(22%) controls had Vitamin D deficiency. Mean serum levels were 48.6 nmol/L ± 24.69. Within group 1, patients with inactive disease (ASDAS <1.3) had vitamin D level 46.8 nmol/L and moderately active disease (ASDAS 1.3-2.0) had vitamin D level of 25.98 ±8.86 nmol/L, high activity group (ASDAS 2.1-3.5) had 18.21±12.03 and very high activity group (ASDAS > 3.5) had 11.18±4.3 nmol/L. Serum 25 OH Vitamin D levels showed moderate inverse linear relationship with ASDAS (coefficient of correlation = -0.642) in our study. Conclusion: Serum Vitamin D levels were low in patients of AS compared to normal healthy controls and disease activity of AS inversely correlates with level of serum vitamin D levels.