Baseline demographic and disease characteristics of patients
| Characteristic | Azathioprine (n=120) | EC-MPS (n=120) |
| Women, n (%) | 111 (92.5) | 108 (90) |
| Age, mean (SD), years | 40.9 (12.9) | 42.1(13.9) |
| Race or ethnic group, n (%) | ||
| White | 120 (100) | 119 (99.2) |
| Asian | 0 (0) | 1 (0.8) |
| Hispanic/Latin American origin | 10 (8.3) | 12 (10) |
| Duration of SLE disease, mean (SD), years | 5.1 (5.6) | 6.2 (7.1) |
| Disease duration ≤2 years at inclusion, n (%) | 52 (43.3) | 49 (40.8) |
| Previous lupus nephritis, n (%)* | 11 (9.2) | 13 (10.9) |
| SLE disease activity | ||
| Total SLEDAI-2K score, mean (SD) | 9.5 (2.9) | 9.9 (4.2) |
| SLEDAI-2K score ≥10, n (%) | 48 (40) | 58 (48.3) |
| PGA score (0–3 VAS), mean (SD) | 1.9 (0.3) | 1.9 (0.4) |
| Total BILAG-2004 index score, mean† (SD) | 19.4 (5.3) | 21.7 (8.2) |
| At least one BILAG A score, n (%) | 51 (42.5) | 63 (52.5) |
| BILAG A/B organ domain score at baseline, n (%) | ||
| Constitutional | 30 (25) | 41 (34.2) |
| Musculoskeletal | 93 (77.5) | 91 (75.8) |
| Mucocutaneous | 88 (73.3) | 78 (65) |
| Cardiorespiratory | 32 (26.7) | 38 (31.7) |
| Renal | 0 (0) | 0 (0) |
| Neuropsychiatric | 3 (2.5) | 4 (3.3) |
| Haematological | 18 (15) | 21 (17.5) |
| Gastrointestinal | 2 (1.7) | 3 (2.5) |
| Ophthalmic | 0 (0) | 2 (1.7) |
| Overall SLICC-DI, median (IQR) | 0.32 (0–4) | 0.43 (0–4) |
| Autoantibody status, n (%) | ||
| ANA titre ≥1/80, no (%) | 120 (100) | 120 (100) |
| Anti-dsDNA antibodies ≥15 IU/mL, n (%) | 65 (54) | 66 (55) |
| Anti-dsDNA antibodies, mean (SD), IU/mL | 194.3(405) | 247.8 (574) |
| Serum C3, mean (SD), mg/dL | 87.3 (34) | 86.9 (28.3) |
| C3 below lower limit of normal (<85 mg/dL), n (%) | 48 (40) | 49 (41) |
| Serum C4, mean (SD), mg/dL | 13.7 (8.8) | 13.1 (8) |
| C4 below lower limit of normal (<10 mg/dL), n (%) | 36 (30) | 44 (37) |
| Previous immunosuppressive therapy, n (%) | ||
| Cyclophosphamide | 6 (5) | 6 (5) |
| Methotrexate/leflunomide | 27 (21.5) | 29 (24.2) |
| Calcineurin inhibitors | 4 (3.3) | 4 (3.3) |
| Mycophenolate mofetil‡ | 5 (4.2) | 5 (4.2) |
| Azathioprine‡ | 4 (3.3) | 3 (2.5) |
| Antimalarial agents, n (%) | 105 (85.3) | 93 (77.5) |
| Corticosteroids use, n (%) | 114 (95) | 116 (96.7) |
| Daily prednisone dose, mean (SD), mg/day | 23.9 (18.1) | 28.6 (21.2) |
| >7.5 mg/day at baseline, n (%) | 103 (85.8) | 98 (81.6) |
*Lupus nephritis was diagnosed in a median time of 9 years (range 6 to 13) before inclusion.
†The total BILAG-2004 index score was based on the updated numerical score proposed for the BILAG-2004 index after the study was initiated (A=12; B=8; C=1; D=0; E=0).34 BILAG A/B in the renal domain was not present at baseline because active nephritis was an exclusion criterion.
‡ Previous mycophenolate mofetil and azathioprine therapy were given mainly for the treatment of lupus nephritis and withdrawn in a median time of 3.5 years (range 3 to 6) before inclusion.
ANA, antinuclear antibodies; BILAG, British Isles Lupus Assessment Group; dsDNA, double-stranded DNA; EC-MPS, enteric-coated mycophenolate sodium; PGA, physician’s global assessment of disease activity; SLE, systemic lupus erythematosus; SLEDAI-2K, Systemic Lupus Erythematosus Disease Activity Index 2000; SLICC-DI, Systemic Lupus International Collaborating Clinics Damage Index.
Reference ranges are as follows: anti-dsDNA antibodies, <15 IU ml; serum C3 (mg/dL), 85 to 110; serum C4 (mg/dL), 10 to 40.