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Background: Among small vessel vasculitis, double-positive patients (DPP), combining serum and/or histologic findings for glomerular basement membrane (GBM) disease, and anti-neutrophil cytoplasmic antibodies (ANCA), is a rare, newly and poorly described condition.
Objectives: We aimed to compare characteristics between DPP and ANCA-associated vasculitis patients (AAVP) with severe-renal-involvement.
Methods: Retrospective multicenter study comparing 33 DPP and 45 severe-renal-involvement (serum creatinine >300 μmol/L) AAVP, all with biopsy-proven nephropathy.
Results: Except for 2 patients (6%) who had pure renal presentation during their entire follow-up period, others exhibited at least one extrarenal manifestation: pulmonary involvement (64%), weight loss (39%), gastrointestinal involvement (33%), ENT manifestations (21%), musculoskeletal symptoms (21%), fever (18%), neurological (12%), cutaneous (6%) and/or cardiac (6%) signs. All DPP (including up to 18% exhibiting negative serum anti-GBM antibodies) presented severe acute kidney failure with histologic GBM involvement. Compared to our AAVP, they had higher serum creatinine (719 versus 501 μmol/L; p=0.006) and a higher of patients requiring initial renal replacement therapy (82% vs 36%; p<0.001). Berden classification significantly differed (p=0.003), with more crescentic glomerulonephritis and fewer sclerotic lesions in DPP. One-year renal survival was significantly lower in DPP than in AAVP (27% versus 64%; p<0.0002). With comparable proportions of ANCA subtypes (2/3 with anti-MPO autoantibodies), numbers of extrarenal manifestations, remission-inducing immunosuppressants and median follow-ups (three years) between groups, relapse rates were similar: 9.1% of DPP and 10% of AAVP. Please, see the
Conclusion: Although DPP have features of both kinds of eponymous vasculitis, the anti-GBM component is the dominant phenotype, with more severe renal presentation and prognosis compared to AAVP with severe renal failure. Simultaneous testing of both antibodies and a systematically performed renal biopsy should be recommended in all rapidly progressive glomerulonephritis patients to recognize this difficult-to-treat, rare disease.
Comparison of clinical characteristics and outcomes between the cohorts of DPP and AAVP
| DPP
| AAVP
| p | |
| Age (year) | 71,5 [14 - 89] | 63 [45 - 93] | 0.14 |
| Male | 16 (48) | 19 (42) | 0.65 |
| Birmingham Vasculitis Activity Score | 18,1 ± 4,8 | 20,4 ± 5,4 | 0.07 |
| Organ involvement (except kidney) | 1,7 ± 0,8 | 1,9 ± 1,1 | 0.31 |
| Serum creatinine (µmol/L) | 719 [238 - 2412] | 501 [310 - 1683] | 0.006 |
| ANCA (MPO/PR3) | 22/11 | 34/11 | 0.45 |
| Berden classification | n = 31 | n = 44 | 0.003 |
| s (sclerotic) / c (crescentic) | 6 (19) / 22 (71) | 12 (27) / 16 (37) | |
| f (focal) / m (mixed) | 0 / 3 (10) | 11 (25) / 5 (11) | |
| Brix renal risk score | n = 27 | n = 44 | 0.000014 |
| Low / Medium / High | 0 (0) / 4 (15) / 23 (85) | 1 (2) / 29 (66) / 14 (32) | |
| Initial immunosuppressive therapy | |||
| IV Cyclophosphamide | 25 (76) | 40 (82) | 0.14 |
| Rituximab | 1 (3) | 3 (7) | 0.64 |
| Plasma exchanges | 25 (76) | 19 (42) | 0.005 |
| Maintenance treatment | 17 (48) | 40 (89) | 0.046 |
| Initial RRT requirement | 27 (82) | 16 (36) | 0.00007 |
| Renal recovery (% initial RRT requirement) | 4 (12) | 6 (38) | 0.9 |
| 1 year renal survival | 9 (27) | 29 (64) | 0.0002 |
Values are displayed as absolute number (%) or as median [range]. DPP: double positive patients; AAVP: ANCA associated vasculitis patients; MPO: myeloperoxidase; PR3: proteinase 3; RRT: renal replacement therapy; IV: intravenous.
Disclosure of Interests: None declared