Patient demographics and ACR classification criteria by cluster
| Clusters | P value | |||||
| 1 (n=20) | 2 (n=32) | 3 (n=15) | 4 (n=53) | 5 (n=34) | ||
| Age at diagnosis (years) (mean±SD) | 42.8±14.5 | 48.8±13.7 | 48.3±16.6 | 40.2±16.3 | 51±12.2 | 0.0083 |
| Female | 19 (95) | 28 (87.5) | 15 (100) | 51 (96.2) | 32 (94.1) | 0.5347 |
| Ethnicity | ||||||
| White or Caucasian | 10 (50) | 11 (34.4) | 4 (26.7) | 14 (26.4) | 16 (47.1) | 0.3981 |
| Black or African–American | 10 (50) | 20 (62.5) | 10 (66.7) | 34 (64.2) | 17 (50) | |
| Other | 0 (0) | 1 (3.1) | 1 (6.7) | 5 (9.4) | 1 (2.9) | |
| Malar | 17 (85) | 15 (46.9) | 6 (40) | 26 (49.1) | 14 (41.2) | 0.0165 |
| Discoid | 7 (35) | 7 (21.9) | 1 (6.7) | 12 (22.6) | 11 (32.4) | 0.2737 |
| Photosensitivity | 8 (40) | 12 (37.5) | 5 (33.3) | 24 (45.3) | 21 (61.8) | 0.2420 |
| Oral ulcer | 8 (40) | 17 (53.1) | 8 (53.3) | 28 (52.8) | 23 (67.7) | 0.3839 |
| Arthritis | 17 (85) | 22 (68.8) | 11 (73.3) | 46 (86.8) | 24 (72.7) | 0.2357 |
| Serositis | 14 (70) | 17 (53.1) | 10 (66.7) | 40 (75.5) | 21 (61.8) | 0.2959 |
| ANA positivity | 20 (100) | 32 (100) | 15 (100) | 53 (100) | 33 (97.1) | 0.6558 |
| Renal disorder | 12 (60) | 18 (56.3) | 8 (53.3) | 38 (71.7) | 12 (35.3) | 0.0214 |
| Neurological disorder | 3 (15) | 4 (12.5) | 5 (33.3) | 6 (11.3) | 2 (5.9) | 0.1499 |
| Haematological disorder | 19 (95) | 25 (78.1) | 11 (73.3) | 44 (83) | 23 (67.7) | 0.1447 |
| Immunological disorder | 20 (100) | 31 (96.9) | 12 (80) | 52 (98.1) | 25 (73.5) | 0.0003 |
| Direct Coombs test | 9 (45) | 5 (15.6) | 5 (35.7) | 12 (24) | 5 (15.2) | 0.0828 |
| Low C3 | 19 (95) | 12 (37.5) | 12 (80) | 53 (100) | 4 (11.8) | <0.0001 |
| Low C4 | 17 (85) | 1 (3.1) | 10 (66.7) | 51 (96.2) | 5 (14.7) | <0.0001 |
| Low CH50 | 3 (15) | 3 (9.7) | 3 (21.4) | 10 (21.7) | 0 (0) | 0.0234 |
Data presented as n (%) or mean±SD.
ACR, American College of Rheumatology.