Circulating GDF15 May Estimate Vasculitis Activity and Predict Poor Outcomes During the Disease Course of ANCA-Associated Vasculitis

<b>Objective:</b> This study investigated whether circulating growth differentiation factor 15 (GDF15) at diagnosis could estimate the Birmingham Vasculitis Activity Score (BVAS) and potentially predict all-cause mortality and end-stage kidney disease (ESKD) during follow-up in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). <b>Methods:</b> This study included 79 patients selected from a cohort of Korean patients with AAV. Circulating GDF15 was measured from patients' sera collected at diagnosis and stored at -80 °C. Clinical data at diagnosis and during follow-up were reviewed. <b>Results:</b> The median age was 64.0 years (40.5% men, and 59.5% women). Median circulating GDF15 was measured as 995.0 pg/mL. Of the 79 patients, 6 (7.6%) died and 20 (25.3%) progressed to ESKD during the disease course. Circulating GDF15 levels were significantly correlated with BVAS (r = 0.340) at diagnosis. Patients with circulating GDF15 ≥ 3350.5 pg/mL exhibited a significantly higher risk of the highest tertile of BVAS than those without (relative risk [RR], 11.229). Similarly, patients with circulating GDF15 ≥ 2239.5 pg/mL and ≥2208.5 pg/mL showed higher risks of all-cause mortality (RR, 7.733) and progression to ESKD (RR 7.125) than those without. Patients with circulating GDF15 ≥ 2239.5 pg/mL and ≥2208.5 pg/mL also showed significantly lower patient and ESKD-free survival rates than those without. <b>Conclusions:</b> Circulating GDF15 at diagnosis is useful in estimating BVAS and potentially predicts all-cause mortality and ESKD progression in patients with AAV.