Risk factors for thrombosis in patients with negative lupus anticoagulant (n = 185). Number of patients tested with and without thrombosis: homocysteine 96% and 99%, hsCRP 100% and 94%, functional protein S and C 42% and 88%, free protein S 42% and 89%, antithrombin III 42% and 88%, fibrinogen 42% and 89%, anti-dsDNA 100% and 99%, anti-Sm 100% and 97%, anti-RNP/Sm 100% and 100%, anti-SSA and anti-SSB 100% and 97%, IgG and IgM aCL and anti-B2GPI 100% and 94%, and aPL double marker 100% and 94%. Values are n (%) or median (minimum–maximum) unless otherwise specified.
| Variables | Thrombosis, n = 24 | No Thrombosis, n = 161 | p |
|---|---|---|---|
| Demographic characteristics | |||
| Female | 21 (88) | 144 (90) | 0.72 |
| Age, yrs | 33 (15–57) | 29 (16–56) | 0.53 |
| Length of followup, yrs* | 0.8 (0–7) | 6 (0–12) | < 0.001 |
| Obesity | 1 (4) | 22 (14) | 0.31 |
| Smoking | 6 (25) | 13 (8) | 0.02 |
| Hypertension | 7 (29) | 26 (16) | 0.15 |
| Diabetes | 2 (8) | 3 (2) | 0.12 |
| Dyslipidemia | 14 (58) | 51 (32) | 0.02 |
| Vascular insufficiency | 1 (4) | 1 (1) | 0.24 |
| Immobilization | 2 (8) | 1 (1) | 0.04 |
| Surgery | 2 (8) | 1 (1) | 0.04 |
| Oral contraceptives | 1 (4) | 12 (7) | 1.00 |
| Menopause | 0 | 2 (1) | 0.34 |
| At least 2 traditional risk factors | 12 (50) | 21 (13) | < 0.001 |
| Serologic characteristics | |||
| Homocysteine, mmol/l | 11 (7–27.8) | 10.5 (5.1–65) | 0.42 |
| hsCRP, mg/dl | 2.81 (0.03–9.85) | 1.11 (0.01–11.40) | 0.05 |
| Functional protein S, % | 67.4 (35.5–130.3) | 77.2 (20.7–130.3) | 0.24 |
| Functional protein S deficiency | 5 (42) | 27 (19) | 0.07 |
| Free protein S, % | 37.2 (16.8–55.8) | 46.4 (15.4–148) | 0.01 |
| Free protein S deficiency | 10 (100) | 136 (96) | 1.00 |
| Functional protein C, % | 123 (23.8–146.2) | 120.3 (52.8–150) | 0.24 |
| Functional protein C deficiency | 1 (10) | 2 (1) | 0.18 |
| Antithrombin III, % | 107.7 (95.8–126.8) | 114.0 (54–126.8) | 0.92 |
| Antithrombin III deficiency | 0 | 5 (4) | 1.00 |
| Fibrinogen, mg/dl | 231.7 (147.5–396.4) | 234.1 (76.1–566.1) | 0.58 |
| SLE characteristics and treatment | |||
| Disease duration, yrs | 0.9 (0–7) | 2 (0–8) | 0.06 |
| Malar rash | 6 (25) | 76 (47) | 0.04 |
| Discoid lupus | 1 (4) | 14 (9) | 0.69 |
| Oral ulcers | 9 (38) | 74 (46) | 0.51 |
| Serositis | 15 (63) | 59 (37) | 0.02 |
| Arthritis | 21 (88) | 149 (91) | 0.70 |
| Photosensitivity | 5 (21) | 56 (35) | 0.24 |
| Renal disorder | 16 (67) | 90 (56) | 0.38 |
| Neurological disorder | 2 (8) | 8 (5) | 0.62 |
| Hematologic disorder | 22 (91) | 122 (76) | 0.11 |
| Immunologic disorder | 21 (88) | 139 (86) | 1.00 |
| ANA | 23 (96) | 144 (89) | 0.47 |
| Vasculitis | 10 (42) | 28 (17) | 0.01 |
| Livedo reticularis | 9 (38) | 23 (14) | 0.009 |
| Nephrotic syndrome | 10 (42) | 27 (17) | 0.01 |
| SLEDAI-2K score | 8 (0–17) | 4 (0–22) | 0.04 |
| SLEDAI, adjusted mean | 4.9 (1.1–10.1) | 4.2 (0–20) | 0.52 |
| SLICC/ACR Damage Index, modified | 0 (0–3) | 0 (0–4) | 0.61 |
| SLICC/ACR Damage Index > 0 | 1 (1–2) | 1 (1–4) | 0.12 |
| Anti-dsDNA antibodies | 13 (54) | 75 (47) | 0.52 |
| Anti-Sm antibodies | 16 (67) | 90 (58) | 0.50 |
| Anti-RNP/Sm antibodies | 13 (54) | 70 (43) | 0.38 |
| Anti-SSA | 14 (58) | 85 (54) | 0.82 |
| Anti-SSB | 7 (29) | 43 (28) | 1.00 |
| IgG aCL | 7 (29) | 31 (20) | 0.42 |
| IgM aCL | 2 (8) | 20 (13) | 0.74 |
| Any aCL | 8 (33) | 40 (26) | 0.46 |
| IgG anti-B2GPI antibodies | 1 (4) | 4 (3) | 0.52 |
| IgM anti-B2GPI antibodies | 0 | 4 (3) | 1.00 |
| Any anti-B2GPI antibodies | 1 (4) | 8 (5) | 1.00 |
| aPL double marker positivity aCL + Anti-B2GPI | 0 | 5 (3) | 1.00 |
| Prednisone | 24 (100) | 157 (98) | 1.00 |
| Current dose of prednisone, mg | 40 (5–262) | 5 (0–100) | < 0.001 |
| Cumulative dose of prednisone, g | 10.6 (0–58) | 11.9 (0–62.1) | 0.51 |
| Methylprednisolone IV | 3 (13) | 23 (14) | 1.00 |
| Azathioprine | 19 (79) | 121 (75) | 0.80 |
| Cyclophosphamide | 7 (29) | 45 (28) | 1.00 |
| Methotrexate | 4 (17) | 21 (13) | 0.74 |
| Mycophenolate mofetil | 1 (4) | 16 (10) | 0.70 |
| Antimalarials | 16 (67) | 108 (67) | 1.00 |
| Aspirin | 6 (25) | 57 (35) | 0.36 |
↵* Length of followup in patients without thrombosis was considered until last visit or death. Significant data are in bold face. hsCRP: high-sensitivity C-reactive protein; IgG: immunoglobulin G; IgM: immunoglobulin M; aCL: anticardiolipin antibodies; anti-B2GPI: anti-β2-glycoprotein I; aPL: antiphospholipid antibodies; SLE: systemic lupus erythematosus; ANA: antinuclear antibodies; SLEDAI: SLE Disease Activity Index; SLICC: Systemic Lupus International Collaborative Clinics; ACR: American College of Rheumatology.