Age, diagnosis delay, organ manifestations and prior diagnoses
| Respondents’ characteristics | Value |
| Age at diagnosis (in years), median (IQR25–75) (data availability: n=4184) | 30 (22–40) |
| Diagnosis delay (years), median (IQR25–75) (data availability: n=4154) | 2 (0–6) |
| Within first year of first symptoms onset, n (%) | 1102 (26.5) |
| Within 2 years, n (%) | 1979 (47.6) |
| Within 5 years, n (%) | 2883 (69.4) |
| Within 10 years, n (%) | 3492 (81.1) |
| Disease manifestations, n (%) (data availability: n=4298) | |
| Joints | 3515 (81.8) |
| Skin | 2551 (59.4) |
| Muscles | 1787 (41.6) |
| Kidney | 1290 (30) |
| Bloodstream (cytopenia) | 1173 (27.3) |
| Lungs | 767 (17.8) |
| Heart | 731 (17) |
| CNS | 696 (16.2) |
| Muscles | 1787 (41.6) |
| Prior diagnosis before that of SLE, n (%) (data availability: n=4275) | |
| Psychological or mental disease | 388 (9.1) |
| UCTD or MCTD | 293 (6.9) |
| Fibromyalgia | 254 (5.9) |
| Sjögren’s disease | 207 (4.8) |
| Antiphospholipid syndrome | 104 (2.4) |
| Other diagnoses (non-autoimmune or rheumatic) | 724 (16.9) |
| Other autoimmune or rheumatic disease | 605 (14.2) |
MCTD, mixed connective tissue disease; UCTD, undifferentiated connective tissue disease.