Clinical features and outcomes of patients with anti-neutrophil cytoplasmic antibody-positive systemic lupus erythematosus from a single-center retrospective study.
INTRODUCTION: The role of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic lupus erythematosus (SLE) remains unclear. ANCA positivity has been linked to more severe disease and possible overlap with ANCA-associated vasculitis, but available data are inconsistent. METHODS: We conducted a retrospective single-center study of SLE patients treated at the University Hospital in Kraków (2012-2022). Patients fulfilled the 2019 EULAR/ACR criteria. ANCA positivity (anti-MPO or anti-PR3) was confirmed by ELISA. Clinical features, laboratory findings, treatment, and outcomes were analyzed. RESULTS: Among 1039 SLE patients, 18 (1.73%) were ANCA-positive (anti-MPO, 72.22%; anti-PR3, 27.78%). Most ANCA-positive SLE patients were female (88.89%), with a median age at disease onset of 35.5 years. The most common manifestations in ANCA-positive cases were hematological abnormalities (100%), constitutional symptoms (88.89%), and joint involvement (88.89%). Renal involvement was observed in 72.22% (n = 13) of ANCA-positive SLE patients; however, lupus nephritis was confirmed by kidney biopsy in only seven cases. Vasculitis was rare (5.56%). Anti-dsDNA (61.11%) and anti-SSA (50%) were the most frequent autoantibodies. No significant differences were found between anti-MPO and anti-PR3 subgroups. Most ANCA-positive patients received glucocorticoids (94.44%), cyclophosphamide (61.11%), and antimalarials (61.11%). No statistically significant differences were observed between the ANCA-positive and ANCA-negative groups (p > 0.05 for all parameters). CONCLUSIONS: ANCA positivity in SLE is rare and predominantly associated with anti-MPO antibodies. It is linked to frequent renal involvement but infrequent vasculitis. No differences were observed between ANCA subtypes, suggesting no distinct clinical phenotype. Key Points • ANCA positivity was rare in this systemic lupus erythematosus cohort (1.73%) and was predominantly associated with anti-MPO antibodies rather than anti-PR3 antibodies. • No significant differences in demographic characteristics, clinical manifestations, comorbidities, or autoantibody profiles were observed between ANCA-positive and ANCA-negative patients. Similarly, no significant differences were identified between the anti-PR3-positive and anti-MPO-positive groups. • ANCA-positive SLE was commonly associated with the need for intensive immunosuppressive treatment, highlighting its potential relevance as a marker of severe disease course.