Basic characteristics of patients with SLE, controls, and SLE-sSS versus SLE-nonsSS.
| Characteristics | SLE | Controls | p | SLE-sSS | SLE-nonsSS | p |
|---|---|---|---|---|---|---|
| N (%) | 504 (100) | 319 (100) | 117 (23.2) | 387 (76.7) | ||
| Basic characteristics, mean ± SD or n (%) | ||||||
| Age, yrs | 46.0 ± 15.2 | 47.4 ± 14.6 | 0.20 | 54.6 ± 13.6 | 43.4 ± 14.7 | < 0.0001 |
| Age at SLE onset, yrs | 33.9 ± 15.5 | ND | ND | 40.4 ± 15.6 | 31.9 ± 14.9 | < 0.0001 |
| Disease duration, yrs | 12.1 ± 12.3 | ND | ND | 14.2 ± 12.8 | 11.5 ± 12.1 | 0.16 |
| No. SLE criteria* | 5.7 ± 1.4 | ND | ND | 5.7 ± 1.5 | 5.7 ± 1.4 | 0.40 |
| Sex, female | 435 (86.3) | 294 (92.2) | 0.01 | 112 (95.7) | 323 (83.4) | 0.0007 |
| Smoking, current | 96 (19.0) | 47 (14.6) | 0.22 | 20 (17.1) | 76 (19.6) | 0.58 |
| Smoking, ever | 258 (51.2) | 151 (46.9) | 0.22 | 62 (53) | 196 (50.6) | 0.65 |
| Primary SS | 108 (21.6) | ND | ND | 25 (21.9) | 83 (21.6) | 0.99 |
| Autoantibody positivity, n (%) | ||||||
| Anti-dsDNA | 190/491 (38.7) | 5/317 (1.6) | < 0.0001 | 36/115 (31.3) | 154/376 (41) | 0.06 |
| Anti-SSA-Ro52 | 140/501 (27.9) | 3/317 (0.9) | < 0.0001 | 56/117 (47.9) | 84/384 (21.8) | < 0.0001 |
| Anti-SSA-Ro60 | 206/499 (41.3) | 5/317 (1.6) | < 0.0001 | 69/117 (59) | 137/382 (35.9) | < 0.0001 |
| Anti-SSB-La | 113/501 (22.6) | 10/317 (3.1) | < 0.0001 | 44/117 (37.6) | 69/384 (18) | < 0.0001 |
| Anti-Sm | 94/501 (18.8) | 1/317 (0.3) | < 0.0001 | 19/117 (16.2) | 75/384 (19.5) | 0.42 |
| Anti-SmRNP | 130/497 (26.2) | 0/317 (0) | < 0.0001 | 29/116 (25) | 101/381 (26.5) | 0.74 |
| Anti-RNP 68 | 51/500 (10.2) | 0/317 (0) | < 0.0001 | 11/117 (9.4) | 40/383 (10.4) | 0.74 |
| Anti-RNP A | 129/496 (26.0) | 10/317 (3.1) | < 0.0001 | 30 (25.6) | 99/379 (26.1) | 0.91 |
| aCL IgG | 108/423 (25.5) | 2/318 (0.6) | < 0.0001 | 24/97 (24.7) | 84/326 (25.8) | 0.83 |
| aCL IgM | 26/432 (6.0) | 1 (0.3) | < 0.0001 | 8/96 (8.3) | 18/336 (5.4) | 0.32 |
| Anti-β2−GPI IgG | 110/417 (26.4) | 2 (0.6) | < 0.0001 | 24/95 (25.3) | 86/322 (26.7) | 0.77 |
| Anti-β2−GPI IgM | 33/434 (7.6) | 1 (0.3) | < 0.0001 | 8/96 (8.3) | 25/338 (7.4) | 0.82 |
| RF IgG | 52/339 (15.3) | 10/261 (3.8) | < 0.0001 | 17/80 (21.2) | 35/259 (13.5) | 0.09 |
| RF IgM | 88/364 (24.2) | 14/283 (4.9) | < 0.0001 | 32/83 (38.6) | 56/281 (19.9) | 0.0005 |
| RF IgA | 109/341 (32.0) | 12/282 (12.4) | < 0.0001 | 34/74 (45.9) | 75/267 (28.0) | 0.004 |
| Other laboratory analyses, mean ± SD or n (%) | ||||||
| IgA, g/l | 2.90 ± 1.46 | 2.30 ± 1.06 | < 0.0001 | 3.19 ± 1.80 | 2.82 ± 1.32 | 0.38 |
| IgG, g/l | 13.63 ± 5.54 | 10.89 ± 2.14 | < 0.0001 | 14.85 ± 5.99 | 13.25 ± 5.35 | 0.009 |
| IgM, g/l | 1.24 ± 1.26 | 1.26 ± 0.69 | 0.0002 | 1.23 ± 1.09 | 1.24 ± 1.31 | 0.89 |
| C3, g/l | 0.88 ± 0.26 | 1.06 ± 0.21 | < 0.0001 | 0.90 ± 0.26 | 0.87 ± 0.26 | 0.33 |
| C4, g/l | 0.15 ± 0.08 | 0.21 ± 0.06 | < 0.0001 | 0.16 ± 0.08 | 0.15 ± 0.07 | 0.16 |
| Lupus anticoagulant | 104 (20.7) | ND | < 0.0001 | 20 (17.1) | 84 (21.8) | 0.27 |
| Cytokines, median (IQR)# | ||||||
| TNF-α, pg/ml | 4.5 (3.1 6.2) | 2.3 (2.0 2.8) | < 0.0001 | 4.9 (3.6 7.1) | 4.4 (3.0 6.0) | 0.008 |
| IL-6, pg/ml | 1.2 (0.7 2.2) | 0.5 (0.4 0.7) | < 0.0001 | 1.5 (0.8 3.0) | 1.1 (0.6 2.0) | 0.009 |
| MCP-4, pg/ml | 78 (53.6 123.8) | 55.8 (40.8 81.1) | < 0.0001 | 94.9 (66.9 131.3) | 74.7 (52.4 120.0) | 0.019 |
| MIP-1β, pg/ml | 72.7 (50.8 108.1) | 43.7 (33.4 56.4) | < 0.0001 | 81.1 (54.8 123.6) | 68.9 (50.3 105.1) | 0.020 |
| IL-12/23p40, pg/ml | 180.6 (122.9 286.3) | 131.0 (99.5 179.3) | < 0.0001 | 211.3 (141.4 363.8) | 177.1 (119.6 274.5) | 0.031 |
| IP-10, pg/ml | 744.4 (457.5 1497.4) | 352.13 (258.9 478.9) | < 0.0001 | 808.0 (536.4 1911.7) | 726.4 (440.8 1471.0) | 0.036 |
| SLE manifestations (ever), n (%)* | ||||||
| Malar rash | 246 (48.8) | 0 (0) | < 0.0001 | 55 (47.0) | 191 (49.4) | 0.65 |
| Discoid lesions | 88 (17.5) | 0 (0) | < 0.0001 | 17 (14.5) | 71 (18.3) | 0.34 |
| Photosensitivity | 318 (63.1) | 57 (17.8) | < 0.0001 | 82 (70) | 236 (61) | 0.07 |
| Oral ulcers | 168/502 (33.5) | 11 (3.4) | < 0.0001 | 41 (35) | 127/385 (33) | 0.67 |
| Arthritis | 406/503 (80.7) | 13 (4.0) | < 0.0001 | 93 (79.5) | 313/386 (81.1) | 0.70 |
| Pleuritis | 185/503 (36.8) | 2 (1) | < 0.0001 | 50 (42.7) | 135/386 (35) | 0.12 |
| Pericarditis | 88/503 (17.5) | 0 (0) | < 0.0001 | 24 (20.5) | 64/386 (16.6) | 0.32 |
| Nephritis | 202/503 (40.2) | 1 (0.3) | < 0.0001 | 37/116 (31.9) | 165 (42.6) | 0.03 |
| Psychosis | 10 (2) | 2 (1) | 0.11 | 1 (1) | 9 (2.3) | 0.46 |
| Seizures | 49 (9.7) | 5 (1.6) | < 0.0001 | 11 (9.4) | 38 (9.8) | 0.89 |
| Leukopenia | 242 (48) | 3 (1) | < 0.0001 | 67 (57.3) | 175 (45.2) | 0.02 |
| Lymphopenia | 273 (54.2) | 2 (1) | < 0.0001 | 68 (58.1) | 205 (53) | 0.32 |
| Thrombocytopenia | 100 (19.8) | 2 (1) | < 0.0001 | 24 (20.5) | 76 (19.6) | 0.83 |
| Raynaud phenomenon | 195 (38.7) | 10 (3.1) | < 0.0001 | 51 (43.6) | 144 (37.2) | 0.21 |
| Vasculitis | 57/498 (11.4) | 0 (0) | < 0.0001 | 9/116 (7.8) | 48/382 (12.6) | 0.15 |
| Interstitial lung disease | 24 (4.8) | 0 (0) | < 0.0001 | 7 (6.0) | 17 (4.4) | 0.47 |
| Peripheral neuropathy | 47/501 (9.4) | 6 (1.9) | < 0.0001 | 18 (15.4) | 29/384 (7.5) | 0.01 |
| Disease activity and damage indices | ||||||
| SLICC/ACR DI > 1 | 314/499 (62.9) | ND | ND | 84/115 (73.0) | 230/384 (59.9) | 0.01 |
| SLAM > 6 | 298/501 (59.5) | ND | ND | 78/116 (67.2) | 220/385 (57.1) | 0.05 |
| SLEDAI > 2 | 356/500 (71.2) | ND | ND | 82/116 (70.7) | 274/384 (71.4) | 0.88 |
When measurements are missing, nos. are given as ratios (no. positive/total no. tested or available). Primary SS: fulfills criteria for primary Sjögren syndrome with the exception that patients are diagnosed with SLE.
↵# Cytokines were determined in 432 patients with SLE and 315 controls.
↵* SLE criteria were determined according to ACR 1982 classification criteria. Values in bold face are statistically significant. SLE: systemic lupus erythematosus; SLE-sSS: SLE patients with secondary Sjögren syndrome; SLE-nonsSS: SLE patients without secondary Sjögren syndrome; aCL: anticardiolipin; Ig: immunoglobulin; β2-GPI: β2-glycoprotein I; C: complement factor; RF: rheumatoid factor; IQR: interquartile range; TNF: tumor necrosis factor; IL: interleukin; MCP: monocyte chemoattractant protein; MIP: macrophage inflammatory protein; IP: interferon γ–induced protein; SLICC/ACR DI: Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index; SLAM: Systemic Lupus Activity Measure; SLEDAI: SLE Disease Activity Index, ND: not determined.