Elevated serum 25-hydroxyvitamin D: a potential indicator of remission in Takayasu arteritis patients with normal ESR and CRP levels.

OBJECTIVE: The goal of the present study was to investigate the correlation between serum 25-hydroxyvitamin D [25(OH)D] levels and disease remission in Takayasu arteritis (TAK) patients.

METHODS: This retrospective study included 59 patients in the study group and 80 patients in the validation cohort with TAK. After 6 months of therapy, patients were re-evaluated, and serum 25(OH)D levels were compared before and after treatment. Correlations between changes in 25(OH)D levels and changes in disease activity scores (NIH, ITAS2010, ITAS.A) were analyzed. Additionally, a predictive cut-off value for disease remission was determined.

RESULTS: After 6 months of therapy, serum 25(OH)D levels in TAK patients significantly increased compared to baseline [(18.33 ± 7.25)µg/L vs (11.77 ± 4.14) µg/L] (P < 0.001). Positive correlations were observed between the increasing changes in the 25(OH)D level and the decreasing changes in the reduced NIH, ITAS2010, and ITAS.A scores (r = 0.455, P < 0.001; r = 0.495, P < 0.001; and r = 0.352 P = 0.006, respectively). A change of 8.45 µg/L in 25(OH)D level was identified as the predictive cut-off value for TAK remission (sensitivity 54.1%, specificity 90.9%, area under the curve = 0.741). Similarly for patients with normal baseline ESR, sensitivity is 68.0%, specificity is 92.3%, and area under the curve is 0.831, and for patients with normal baseline CRP, sensitivity is 58.3%, specificity is 90.0%, and area under the curve is 0.748. Validation in an additional 80 patients demonstrated a higher remission rate in those with a 25(OH)D level change > 8.45 µg/L.

CONCLUSION: Serum 25(OH)D levels significantly increased after treatment in TAK patients, and an increase of ≥ 8.45 µg/L was predictive of disease remission, especially in individuals with normal baseline ESR and/or CRP levels. Key Points • Following treatment, there was a significant increase in serum 25(OH)D levels among TAK patients. • The elevated changes in 25(OH)D levels before and after treatment demonstrated a positive correlation with the reduction in disease activity scores. • In patients with TAK before and after treatment, an elevation in serum 25(OH)D levels exceeding 8.45 µg/L serves as an indicator for disease remission, particularly prominent in individuals with normal baseline ESR and/or CRP levels.