| NHS | NHSII | |
| (a) Systemic lupus erythematosus | n = 118 | n = 72 |
| Mean (SD) age at diagnosis, years | 53.6 (8.2) | 42.1 (5.3) |
| Anti-nuclear antibody positive,‡ n (%) | 112 (96%) | 72 (100%) |
| Anti-dsDNA antibody positive,* n (%) | 18 (15%) | 39 (54%) |
| Arthritis, n (%) | 23 (19%) | 48 (67%) |
| Haematological involvement, n (%) | 23(19%) | 40 (56%) |
| Renal involvement, n (%) | 3 (3%) | 4 (6%) |
| Mean (SD) number of ACR criteria† | 4.6 (1.0) | 4.7(1.1) |
| Diagnosed by ACR member | 87 (74%) | 65 (90%) |
| (b) Rheumatoid arthritis | n = 559 | n = 163 |
| Mean (SD) age at diagnosis, years | 58.0 (8.6) | 44.1 (5.4) |
| Rheumatoid factor positive, n (%) | 318 (57%) | 95 (58%) |
| Rheumatoid nodules, n (%) | 69 (12%) | 18 (9%) |
| Radiographic changes, n (%) | 156 (28%) | 42 (26%) |
| Mean (SD) number of ACR criteria* | 4.6 (0.8) | 4.5 (0.7) |
| Diagnosed by ACR member | 461 (84%) | 155 (95%) |
ACR, American College of Rheumatology.
*Anti-double-stranded DNA antibody positive by medical record review.
†Four of 11 criteria required for diagnosis of systemic lupus erythematosus by ACR criteria.24 25
‡Antinuclear antibody ⩾1:40 by medical record review.
§Four of seven criteria required for diagnosis of rheumatoid arthritis by ACR criteria.26
NHS, Nurses' Health Study; NHSII, Nurses' Health Study II.