Unclassifiable repeated antineutrophil cytoplasmic antibody (ANCA) positivity in diseases other than ANCA-associated vasculitis

Infections and systemic vasculitis

Infections and systemic vasculitis (SV) are characterized by mutual influence, which increases the risk of occurrence, aggravates the course and outcome of the disease. The review considers the issues related to both the trigger role of infections in the development of SV and comorbid infections (CI) that complicate the course of the disease. Recognition of the infectious etiology of SV is of great importance, since it requires a comprehensive examination and, if necessary, early and complete etiotropic treatment. Since SV per se and the use of both induction and maintenance immunosuppressive therapy are significant risk factors for secondary CIs, special attention should be paid to the prevention of the latter, including vaccination, primarily against influenza and pneumococcal infections.

Clinical Significance of Antineutrophil Cytoplasmic Antibody Positivity in Patients Infected with SARS-CoV-2

Objectives: To investigate the rate of antineutrophil cytoplasmic antibody (ANCA) positivity and its clinical significance in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: This study included 178 patients infected with SARS-CoV-2 who were enrolled in a cohort at a single centre. Myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA levels in stored blood sera were measured using immunoassay kits. Mortality, mechanical ventilator care, and severe infection were assessed as three poor outcomes. The 2022 American College of Rheumatology and the European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria for the three subtypes of AAV were applied only to patients who had MPO-ANCA or PR3-ANCA among study subjects. Results: The detection rate of ANCA positivity was 18.5%. MPO-ANCA and PR3-ANCA were found in 22 (12.4%) and 14 (7.9%) patients, respectively. However, neither MPO-ANCA nor PR3-ANCA affected the three poor outcomes. According to the new criteria, 12 (6.7%) and 21 (11.8%) patients were classified as having granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), respectively. Conclusions: SARS-CoV-2 infection may increase the rate of ANCA positivity. Although it might not affect poor outcomes, it might contribute to the classification of GPA and MPA despite uncertain clinical significance.

A retrospective analysis of antineutrophil cytoplasmic antibody-associated vasculitis aiming for an equation prediction end-stage renal disease

We provided a predictable method that measures the risk of progression to end-stage renal disease (ESRD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) by using a few routine serum markers of kidney functions at diagnosis. In a retrospective cohort study, the medical records of 254 AAV patients were reviewed. We derived a novel equation for the prediction of the progression to ESRD using variables with a P-value < 0.1 in the multivariable Cox hazard model analysis. We assigned a weight to each variable according to the slopes like a coefficient of a linear equation. The median age of the AAV patients was 59 years and 42 AAV patients progressed to ESRD. In the multivariable Cox analysis using variables with significance in the univariable analysis, MPO-ANCA (or P-ANCA) positivity, blood urea nitrogen, serum creatinine, and serum albumin tended to be associated with the progression to ESRD (P-value < 0.1). We develop an Equation for predicting ESRD in AAV (EPEA) using those variables with the slope of each one. When the cut-off of EPEA was set as -0.094, AAV patients with EPEA ≥ -0.094 had a significantly higher risk of progression to ESRD than those with EPEA < -0.094 (RR, 39.622). AAV patients with EPEA ≥ -0.094 exhibited a significantly lower ESRD-free survival rate than those with EPEA < -0.094. We provided a method to obtain EPEA and demonstrated its predictive potential for ESRD in immunosuppressive drug-naïve AAV patients. Key points • A novel equation for the prediction of the progression to ESRD was developed using variables with a P-value < 0.1 in the multivariable Cox hazard model analysis. A weight was assigned to each variable according to the slopes like a coefficient of a linear equation. • An optimal cut-off of EPEA for progression to ESRD was obtained using the receiver operator characteristic (ROC) curve analysis. • AAV patients with EPEA more than the cut-off had a significantly higher risk of progression to ESRD than those without (RR, 39.622). • AAV patients with EPEA more than the cut-off exhibited a significantly lower ESRD-free survival rate than those without.