A prognostic immune nutritional index can predict all-cause mortality in patients with antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND: Studies have proposed that nutritional and immune-related markers are relevant with patient outcomes of various medical conditions and could be a useful indicator of patient prognostication. OBJECTIVES: This study investigated whether a prognostic immune nutritional index (PINI) at diagnosis could predict adverse clinical outcomes in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). DESIGN: A retrospective, single-centre observational cohort analysis of patients with AAV. METHODS: All-cause mortality and end-stage renal disease (ESRD) were investigated outcomes during the observation period. PINI was calculated by serum albumin (g/mL) × 0.9 − monocyte count (/mm(3)) × 0.0007, and the optimal cut-off of PINI was obtained using a Youden index-based bootstrapping method. Cox hazard analyses were performed to identify independent predictors of patient outcomes. RESULTS: Of the 250 eligible patients, the median age of patients was 60.0 years, and 34.0% were men. During the disease course, 33 (13.2%) died and 42 (16.8%) developed ESRD, respectively. The ideal PINI cut-offs for all-cause mortality and ESRD were set as ⩽2.47 and ⩽3.12 (sensitivity and specificity of 75.1% and 60.6% for mortality and 46.2% and 78.6% for ESRD). AAV patients with PINI ⩽2.47 and those with PINI ⩽3.12 exhibited significantly higher rates for all-cause mortality and ESRD compared to those with PINI >2.47 and >3.12. In the multivariable Cox analysis, PINI ⩽2.47 (hazard ratio [HR]: 3.173, 95% confidence interval [CI]: 1.129, 8.916, p = 0.029) was independently associated with all-cause patient mortality; however, PINI ⩽3.12 was not independently associated with ESRD (HR: 1.097, 95% CI: 0.419, 2.870, p = 0.850). CONCLUSION: Findings from this study demonstrated PINI could predict all-cause patient mortality in AAV, and a higher clinical attention is warranted in those with PINI ⩽2.47 at initial diagnosis.