Background: We investigated whether large unstained cell (LUC) count could estimate the current high activity according to Birmingham vasculitis activity score (BVAS) in patients with antineutrophil cytoplasmic antibody (ANCA) positive ANCA-associated vasculitis (AAV). Methods: We retrospectively reviewed the medical records of 176 immunosuppressive drug-naïve patients with ANCA positive AAV. Clinical and laboratory data at diagnosis, including LUC count, were collected. High BVAS was defined as the highest tertile of BVAS (BVAS ≥ 15) in this study. Results: The median age was 61.0 years, and 64.8% were female. The median LUC count was 60.0 mm3, and LUC was detected in 106 patients. LUC count was significantly correlated with BVAS, age, white blood cell count, haemoglobin, platelet count, serum albumin, erythrocyte sedimentation rate and C-reactive protein. Overall, the median BVAS in AAV patients with LUC positivity was significantly higher than that in those without (14.0 vs 10.0). When the cut-off of LUC count for the current high BVAS was set as BVAS ≥ 15 mm3, AAV patients with LUC count ≥ 15 mm3 had a significantly higher risk for the current high BVAS than those with LUC count < 15 mm3 (relative risk 2.596). However, in the multivariable linear and logistic regression analyses, LUC did not seem to estimate the current BVAS independently among clinical and laboratory variables. Conclusion: LUC count was significantly correlated with the current BVAS and LUC count ≥ 15 mm3 could estimate the current high BVAS in patients with ANCA positive AAV.
Bibliographical noteFunding Information:
This study was supported by a faculty research grant of Yonsei University College of Medicine (6‐2019‐0184) and a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (HI14C1324).
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