Clinical and Immunological Factors Associated with Disease Activity in MPO-ANCA-Associated Vasculitis

To explore clinical and immunological factors associated with disease activity in myeloperoxidase‑antineutrophil cytoplasmic antibody‑associated vasculitis (MPO‑AAV), and analyze cross‑sectional correlations of renal impairment, anemia and antinuclear antibodies (ANA) with disease activity.

In this retrospective study, 82 consecutive hospitalized MPO‑AAV patients (September 2023‑February 2025) were stratified into high‑ and low‑activity groups using BVAS‑3 (cut‑off >15 points). Baseline clinical and laboratory data were compared. Spearman correlation and univariate‑multivariate logistic regression were applied to evaluate correlates of high disease activity.

Compared with low‑activity patients, the high‑activity group had higher serum creatinine (172.5 (86.2-310.7) vs 72.1 (52.3-103.5)), lower eGFR (46.70 ± 36.53 vs 86.92 ± 27.29) and hemoglobin (90.54 ± 20.53 vs 110.69 ± 18.43) (all P<0.001), as well as a higher rate of kidney injury (69.57% vs 13.89%, P<0.001). ANA positivity showed only marginal inter‑group difference (P=0.075). BVAS‑3 was strongly correlated with creatinine (r= 0.621(0.461~0.743)), eGFR (r= -0.712(-0.801~ -0.593)), and hemoglobin (r= -0.589(-0.716~ -0.419)) (all P<0.001). Multivariate regression identified kidney injury (OR=17.75, 95% CI 3.63‑86.97, P<0.001) and reduced hemoglobin (OR=0.93, 95% CI 0.89‑0.98, P=0.005) as independent correlates. ANA positivity reached significance in multivariate analysis (OR=7.30, 95% CI 1.13‑47.37, P=0.038), but this result should be interpreted cautiously due to small sample and wide confidence intervals.

In this single‑center retrospective MPO‑AAV cohort, renal injury and lower hemoglobin were independently associated with higher cross‑sectional disease activity.