Introduction:
Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a heterogeneous group of small-vessel vasculitides characterised by systemic inflammation and multi-organ involvement. This study aimed to investigate the prognostic and clinical significance of haematological and biochemical indices – namely the neutrophil-to-lymphocyte ratio, platelet- to-lymphocyte ratio (PLR), haemoglobin–albumin–lymphocyte–platelet (HALP) score, neutrophil- to-albumin ratio, systemic immune-inflammation index (SII), C-reactive protein-to-albumin ratio, and albumin-to-globulin ratio (AGR) – measured at the time of diagnosis. We sought to determine their associations with disease activity, organ involvement, and overall prognosis in patients with AAV.

Material and methods:
A retrospective cohort study was conducted on 56 patients diagnosed with AAV between January 2020 and August 2025, according to the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria. Demographic, clinical, and laboratory data were extracted from medical records. Inflammatory and nutritional indices were calculated at diagnosis, and their correlations with disease activity (Birmingham Vasculitis Activity Score – BVAS), prognosis (Five-Factor Score – FFS), organ involvement, relapse, and mortality were analysed using appropriate statistical tests, including Spearman correlation and receiver operating characteristic analysis.

Results:
The mean age was 54.2 ±15.7 years, and 73.2% of patients had granulomatosis with polyangiitis. Renal and pulmonary involvements were most common. The relapse rate was 32%, and mortality was 12.5%. None of the indices showed significant predictive ability for relapse (area under the curve < 0.6). A moderate negative correlation was found between FFS and AGR ( = –0.31, p = 0.02) and between BVAS and HALP ( = –0.33, p = 0.01). The HALP and AGR were significantly lower in renal involvement, while PLR and SII were higher and HALP lower in pulmonary involvement.

Conclusions:
Inflammatory and nutritional indices at diagnosis may not predict relapse in AAV but may reflect disease activity and organ-specific involvement. These easily accessible parameters could serve as complementary biomarkers for early risk stratification, warranting validation in large prospective studies.