Baseline characteristics of study participants according to treatment group. Values are number (%) unless otherwise indicated.
| Characteristic | Intervention, n = 178 | Placebo, n = 89 | p |
|---|---|---|---|
| Age, yrs, mean (SD) | 38.8 (5.7) | 38.9 (3.5) | 0.78 |
| Sex, female/male, no. | 152/26 | 76/13 | — |
| Body mass index, kg/m2, mean (SD) | 24.1 (6.6) | 23.9 (7.1) | 0.19 |
| Dietary calcium, mg/day, mean (SD) | 637 (329) | 635 (338) | 0.64 |
| 25 hydroxyvitamin D, ng/ml, mean (SD) | 19.9 (16.3) | 19.8 (16.7) | 0.71 |
| Serum creatinine, mg/dl, mean (SD) | 1.3 (0.4) | 1.1 (0.7) | 0.85 |
| Serum calcium, mg/dl, mean (SD) | 9.3 (0.5) | 9.3 (0.4) | 0.22 |
| Disease duration, yrs, mean (SD) | 8.3 (6.9) | 8.2 (6.7) | 0.17 |
| Current sun protection use | 121 (68) | 61 (69) | 0.56 |
| Sun exposure/day, | |||
| ≥ 15 min | 138 (78) | 70 (79) | 0.58 |
| ≤ 15 min | 40 (22) | 19 (21) | 0.45 |
| Photosensitivity | 118 (66) | 59 (66) | 0.59 |
| SLEDAI score at vitamin D measurement, mean (SD) | 4.8 (3.4) | 4.7 (3.6) | 0.39 |
| ANA-positive (%) | 81 | 80 | 0.65 |
| Anti-dsDNA-positive (%) | 86 | 85 | 0.87 |
| Anti-Sm positive (%) | 25 | 24 | 0.66 |
| Anti-cardiolipin IgG-positive (%) | 22 | 21 | 0.65 |
| IgM-positive (%) | 18 | 17 | 0.59 |
| C4, mg/l, mean (SD) | 0.166 (0.091) | 0.168 (0.089) | 0.65 |
| Medications | |||
| Corticosteroids, mg, mean dose (SD) | 10.0 (6.1) | 9.9 (5.8) | 0.48 |
| Antimalarial use (HCQ) | 144 (81) | 72 (81) | 0.51 |
| Immunosuppressants (AZA) | 46 (26) | 24 (27) | 0.46 |
| ACE inhibitors/ARB | 48 (27) | 25 (28) | 0.55 |
| Renal disease | 45 (25) | 22 (25) | 0.33 |
| Nervous system | 14 (8) | 6 (7) | 0.71 |
| Serositis | 16 (9) | 9 (10) | 0.82 |
| Hematological | 117 (66) | 58 (65) | 0.47 |
| Polyarthritis | 115 (65) | 59 (66) | 0.39 |
| Skin involvement | 110 (62) | 55 (62) | 0.75 |
SLEDAI: Systemic Lupus Erythematosus Disease Activity Index; ANA: antinuclear antibodies; AZA: azathioprine; HCQ: hydroxychloroquine; ACE: angiotensin-converting enzyme; ARB: angiotensin receptor blockers.