Demographic, clinical and laboratory features of patients at baseline
| Characteristics at baseline | Whole cohort n=66 | HCQ >5 mg/kg n=39 | HCQ ≤5 mg/kg n=27 |
| Sex, female | 65 (99) | 38 (99) | 27 (100) |
| Age, years, mean (SD) | 42.01±11.2 | 43.5±10.9 | 41.2±12.2 |
| Disease duration, years, mean (SD) | 15.71 (9.02) | 15 (8.3) | 15 (8.2) |
| SLEDAI, median (range) | 2 (0–4) | 2 (0–4) | 2 (0–4) |
| SDI, median (range) | 0 (0–2) | 0 (0–2) | 0 (0–1) |
| (HCQm) ng/mL, median (range) | 512.60 (104.41–3105.66) | 617.8 (104.4–3105.6) | 580.8 (121.6–1214.2) |
| HCQ daily dose mg/kg, mean (SD) | 5.4±1.1 | 6.1±0.6 | 4.2±0.8 |
| Time remission, years, median (range) | 2.00 (1–11) | 2.00 (1–10) | 2.00 (1–11) |
| Previous renal involvement | 31 (47) | 18 (46) | 13 (48) |
| Time HCQ, years, median (range) | 5 (0–32) | 5 (0–32) | 4 (0–30) |
| Glucocorticoids | 33 (50) | 22 (56) | 11 (40) |
| Prednisone equivalent mg/day, median (range) | 2.5 (0–5) | 2.5 (0–5) | 2.5 (0–5) |
| Mycophenolate mofetil | 6 (9) | 4 (10) | 2 (7) |
| Azathioprine | 7 (11) | 5 (12) | 2 (7) |
| Methotrexate | 1 (2) | 1 (2) | 0 |
| Ciclosporin | 2 (3) | 1 (2) | 1 (3) |
| Belimumab | 1 (2) | 1 (2) | 0 |
HCQ, hydroxychloroquine; SDI, Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index of SLE; SLEDAI, SLE Disease Activity Index.