Table 1.
Clinical and immunological features of the 441 included patients
| Patient characteristics | Discovery cohort (n = 236) | Replication cohort (n = 205) | Mann–Whitney U test or chi-square test, p value |
|---|---|---|---|
| Background variables | |||
| Female, % (n) | 88% (207) | 89% (183) | N.S. |
| Age, years, median (range) | 54 (19–94) | 42 (13–80) | <0.001 |
| Disease duration, years, median (range) | 15 (0–52) | 8 (0–32) | <0.001 |
| Caucasian ethnicity, % (n) | 93% (219) | 69% (142) | <0.001 |
| Conventional radiology available, % (n) | 43% (102) | N.A. | |
| Erosions on x-ray, % (n) | 4.2% (10)a | N.A. | |
| HAQ score (median, range) | 0.13 (0-3) | N.A. | |
| Ever smoker (former or current), % (n) | 45% (107) | 43% (88) | N.S. |
| Meeting ACR-82, % (n) | 85% (201) | 91% (188) | 0.038 |
| Meeting SLICC-12, % (n) | 99% (233) | 99% (203) | N.S. |
| Clinical phenotypes (SLICC-12 definitions on criteria 1 − 11), % (n) | |||
| 1) Acute cutaneous lupus | 45% (106) | 53% (108) | N.S. |
| 2) Chronic cutaneous lupus | 15% (36) | 18% (36) | N.S. |
| 3) Oral ulcers | 12% (29) | 32% (66) | <0.001 |
| 4) Non-scarring alopecia | 22% (51) | 19% (39) | N.S. |
| 5) Synovitis | 76% (180) | 70% (143) | N.S. |
| 6) Serositis | 37% (87) | 23% (48) | 0.003 |
| Pleuritis | 35% (83) | 18% (37) | <0.001 |
| Pericarditis | 14% (34) | 14% (28) | N.S. |
| 7) Renal | 28% (66) | 26% (53) | N.S. |
| 8) Neurologic | 11% (26) | 22% (44) | 0.004 |
| Seizures | 4.2% (10) | 5.4% (11) | N.S. |
| Psychosis | 1.7% (4) | 4.4% (9) | N.S. |
| Mononeuritis multiplex | 0.4% (1) | 0% (0) | N.S. |
| Myelitis | 0.4% (1) | 2.9% (6) | N.S. |
| Peripheral or cranial neuropathy | 5.1% (12) | 8.3% (17) | N.S. |
| Acute confusional state | 0.8% (2) | 2% (4) | N.S. |
| 9) Haemolytic anaemia | 4.7% (11) | 5.9% (12) | N.S. |
| 10) Leukopenia and/or lymphopenia | 52% (122) | 30% (62) | <0.001 |
| 11) Thrombocytopenia | 12% (28) | 18% (37) | N.S. |
| Raynaud | 26% (61) | 40% (82) | 0.002 |
| Interstitial lung disease | 3.5% (8) | 3.4% (7) | N.S. |
| Immunological features (SLICC-12 definitions on criteria 1 to 6), % (n) | |||
| 1) Antinuclear antibody (ANA) | 100% (236) | 100% (205) | N.S. |
| 2) Anti-dsDNA antibody (anti-dsDNA) | 50% (118) | 56% (115) | N.S. |
| 3) Anti-Smith antibody (anti-Sm) | 8.1% (19) | 10% (21) | N.S. |
| 4) Antiphospholipid antibody | 59% (139) | 44% (90) | 0.002 |
| Lupus anticoagulant | 35% (69)b | 32% (65) | N.S. |
| Anti-cardiolipin antibody | 34% (80) | 24% (49) | 0.027 |
| Anti-β2-glycoprotein I antibody | 26% (62) | 18% (27)c | N.S. |
| 5) Low complement | 53% (124) | 50% (102) | N.S. |
| 6) Direct Coombs test | 56% (59)d | 23% (38)e | <0.001 |
| Anti-small nuclear ribonucleoprotein antibody (anti-snRNP) | 37% (88) | 17% (35) | <0.001 |
| Anti-Ro/Sjögren’s syndrome A antibody (SSA) | 37% (88) | 42% (87) | N.S. |
| Anti-La/Sjögren’s syndrome B antibody (SSB) | 28% (66) | 13% (27) | <0.001 |
| Anti-cyclic citrulline peptide antibody (anti-CCP)f | 6.8% (16) | 5.4% (11) | N.S. |
| Anti-carbamylated protein antibody (anti-CarP) | 9.8% (23) | 8.3% (17) | N.S. |
| Rheumatoid factorf | 25% (26)d | 15% (31) | 0.046 |
aCalculated in 236 patients. bData available on 195 patients. cData available on 148 patients. dData available on 107 patients. eData available on 164 patients. fNot performed with identical assays. HAQ health assessment questionnaire, ACR American College of Rheumatology, SLICC Systemic Lupus Erythematosus International Collaborating Clinics, ANA antinuclear antibodies, dsDNA double-stranded DNA, N.A. not applicable, N.S. not significant