Long-term kidney outcome of patients with rheumatological diseases and antineutrophil cytoplasmic antibody-glomerulonephritis: comparison with a primitive ANCA-glomerulonephritis cohort

Objective Antineutrophil cytoplasmic antibody (ANCA) may appear in the course of rheumatic diseases (RD) but the kidney involvement is very rare and the prognosis poorly defined. Methods We retrospectively identified patients with RD among 153 patients with ANCA glomerulonephritis (ANCA-GN). Their clinical/histological presentation and outcome were compared with that of primitive ANCA-GN patients (1:4) matched for sex, age, ANCA type and follow-up. Results Nine patients (5.9%) were included: three had rheumatoid arthritis, two systemic sclerosis, two psoriatic arthritis, one ankylosing spondylitis and one seronegative spondylarthritis. Seven patients were MPO positive, two PR3 positive. ANCA-GN developed 74 months after RD with microscopic haematuria and acute kidney dysfunction in all but two patients. After 68-month follow-up, four patients (44.4%) achieved response to therapy defined as eGFR >60/min/1,73 m2 or stable, no microscopic haematuria and negative ANCA. At ANCA-GN diagnosis, serum creatinine and C-reactive protein were significantly lower in RD-ANCA-GN (2.38 vs. 3.34mg/dl, p=0.05 and 2.3mg/dl vs. 7.2mg/dl; p=0.05, respectively) while haemoglobin was higher (12.3g/dl vs. 9.3g/dl p<0.01) than in the 36 primitive ANCA-GN patients of control group. At kidney biopsy, focal forms were more frequent in RD patients (44.45% vs. 18.75%, p=0.11). The treatment between the two groups was not significantly different. At last observation, the percentage of patients with ESKD was lower in RD than in controls (11.1%vs. 30.5%; p=0.23). Conclusion Patients with RD seem to develop ANCA-GN with less severe clinical/histological kidney involvement, and better long-term kidney survival than primitive ANCA-GN. This is probably due to the strict monitoring of RD patients that allows a prompter ANCA-GN diagnosis and treatment.