Table 1 Characteristics and descriptive data for patients with systemic lupus erythematosus (SLE) and ANCA-associated vasculitis (AAV)
|  | SLE (n = 160) | AAV (n = 30) |
|---|---|---|
Background variables | ||
 Age (mean (SD)) | 59 (18) | 66 (11) |
 Female gender, n (%) | 139 (87) | 14 (47) |
Ongoing pharmacotherapy | ||
 Glucocorticoids, n (%) | 110 (69) | 22 (73) |
 Methotrexate, n (%) | 18 (11) | 2 (7) |
 Mycophenolate mofetil, n (%) | 22 (14) | 1 (3) |
 Rituximab, n (%) | 9 (6) | 7 (23) |
 Hydroxychloroquine, n (%) | 103 (64) | 0 (0) |
 Other immunosuppressants, n (%) | 21 (13) | 0 (0) |
Disease variables | ||
 Disease duration, years (mean (SD)) | 21 (11) | 0.77 (3.8) |
 SLEDAI-2K (median (IQR)) | 4 (1–8) | – |
 SDI (median (IQR)) | 1 (0–2) | – |
 Birmingham Vasculitis Activity Score (median (IQR)) | – | 14 (12–18) |
 Microscopic polyangiitis, n (%) | – | 14 (47) |
 Granulomatosis with polyangiitis, n (%) | – | 16 (53) |
 New-onset (N) or established/recurrent (R) disease, n (%) | N: 5 (3) R: 155 (97) | N: 27 (90) R: 3 (10) |
Clinical laboratory variables | ||
 Hemoglobin, g/L (mean (SD)) | 129 (14) | 108 (13) |
 Leukocyte count, 109/L (median (IQR)) | 6.3 (4.7–8.3) | 11.7 (8.2–15.4) |
 Erythrocyte sedimentation rate, mm/h (median (IQR)) | 16 (7–33; n = 155) | 86 (39–100; n = 19) |
 Plasma creatinine, µmol/L (median (IQR)) | 67 (57–78) | 126 (78–287) |
 Estimated GFR, ml/min/1.73 m2 (median (IQR)) | 79 (62–92) | 48 (17–69) |
 Anti-C1q antibodies, units (median (IQR)) | 6.4 (3.9–19.9) | – |
 Anti-C1q antibody positive, n (%; ref < 20) | 40 (25) | – |
 MPO-ANCA, IU/mL (median (IQR)) | – | 0.6 (0.3–55) |
 MPO-ANCA positive, n (%; ref < 3.5) | – | 14 (47) |
 PR3-ANCA, IU/mL (median (IQR)) | – | 9.8 (0.3–70) |
 PR3-ANCA positive, n (%; ref < 2) | – | 16 (53) |
 aAnemia, n (%) | 36 (23) | 26 (87%) |
 Hematuria, n (%) | 47 (30; n = 155) | 23 (82; n = 28) |
 Albuminuria, n (%) | 29 (18; n = 156) | 12 (43; n = 28) |
Clinical features (ACR–82 defined) | ||
 1. Malar rash, n (%) | 59 (37) | – |
 2. Discoid rash, n (%) | 29 (18) | – |
 3. Photosensitivity, n (%) | 87 (54) | – |
 4. Oral ulcers, n (%) | 17 (11) | – |
 5. Arthritis, n (%) | 129 (81) | – |
 6. Serositis, n (%) | 58 (36) | – |
 7. Renal disorder, n (%) | 45 (28) | – |
 8. Neurologic disorder, n (%) | 11 (7) | – |
 9. Hematologic disorder, n (%) | 97 (61) | – |
 10. Immunologic disorder, n (%) | 91 (57) | – |
 11. IF-ANA, n (%) | 157 (98) | – |