Prognostic nutritional index is associated with disease severity and relapse in ANCA‐associated vasculitis

Abstract Aim The prognostic nutritional index (PNI), calculated by serum albumin and peripheral blood lymphocyte count, is considered to reflect immune‐related nutritional status. In this study, we first investigated the clinical significance of PNI in patients with antineutrophil cytoplasmic antibody‐associated vasculitis (AAV). Method Medical records of 160 patients classified as AAV from October 2000 to September 2017 were reviewed. We calculated the Birmingham vasculitis activity score (BVAS) and collected laboratory data including erythrocyte sedimentation rate (ESR), C‐reactive protein (CRP) level, white blood cell, lymphocyte, and platelet counts, and serum albumin, aspartate aminotransferase, and alanine aminotransferase levels at diagnosis. PNI at diagnosis was calculated as (10 × serum albumin [g/dL] + 0.005 × lymphocyte count [/mm 3 ]). Associations between laboratory variables, PNI, and BVAS were assessed by linear regression analyses, and Cox proportional hazard analysis was used to evaluate factors associated with disease relapse. Results The mean age was 55.2 years and 48 patients (30.0%) were male. In univariable linear regression analysis, BVAS was positively correlated with ESR and CRP and negatively with lymphocyte count, serum albumin, and PNI ( r = −0.307). In multivariable linear regression analysis, among ESR, CRP, and PNI, PNI was associated with BVAS ( β = −0.299). PNI also significantly correlated with the included laboratory data. In Cox proportional hazard analysis, myeloperoxidase—antineutrophil cytoplasmic antibody positivity (odds ratio [OR] 2.875, P = 0.003) and PNI ≤36.75 (OR 2.066, P = 0.042) revealed to be independent predictors of disease relapse during the follow‐up period. Conclusions Prognostic nutritional index at diagnosis might be useful for assessing disease severity and predicting the prognosis of AAV patients.