Background Antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis (AAV) is a necrotizing vasculitis that predominantly affects small vessels and is associated with ANCA specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA). The major clinicopathologic variants of AAV include microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA). Recent studies have demonstrated the crucial role of complement activation in the pathogenesis of AAV. However, the clinical characteristics of AAV with hypocomplementemia (HC) still remain unclear.
Objectives The aim of our study was to anlyze the demographic, laboratory, treatment and clinical characteristics of AAV using medical records. To compare the AAV patients with and without HC.
Methods Retrospective study of patients with AAV diagnosed and followed in a specific Systemic Autoimmune Diseases and Thrombosis Unit. We defined HC as the state in which at least one of the following was lower than the lower limit of the normal range: Complement 3 (C3), Complement 4 (C4). Demographic, clinical, treatment and evolution data were recorded and analyzed using SPSS 22.0.
Results Thirty-six patients with AAV were included (94,4% MPO-ANCA, 5,6% PR3-ANCA). 8 patients were diagnosed of GPA, 21 of MPA and 3 of EGPA. 61,1% of the patients were males and the mean age at the onset of the disease was 63,11±14,38 years [30–85]. 75% of patients had any vascular risk factors. Renal involvement occurred in 32 patients (88,9%): hematuria in 96,9%, proteinuria in 90,6% (>1 gr 68,7%) and glomerular filtration decreased in 81,25%. Biopsy was performed in 22 patients and a focal and segmental necrotizing glomerulonephritis with extracapillary proliferation was the finding more common. Pulmonary disease (61,1%) included interstitial disease 40,9%, alveolar hemorrhage 22,7% and nodules 18,2%. Other clinical manifestations were constitutional syndrome 36,1% (the main symptom was asthenia); ear, nose, and throat manifestations 33.3%; neurologic involvement 27.8% (the main finding was polyneuropathy); articular manifestations 33.3% and skin lesions 16,7%. All the patients received prednisone in combination with cyclophosphamide (69.4%) or rituximab (13.9%). Azathioprine was used as glucocorticoid-sparing agent (41.7%). 83.3% of the patients needed hospital admission and 6 died (16.7%). Eleven patients (30,6%) had HC at their diagnosis of AAV. Compared to the AAV patients without HC (n=25), we found no significant differences in the outcome or severity of the manifestations (evaluated by Five factor score). The small sample size could in part explain these results.
Conclusions Our patients with HC at diagnosis of AAV did not have different characteristics than those without HC. More studies are needed to determinate if HC is a predictor of poor prognosis in AAV patients.
Disclosure of Interest None declared