Table 1.
Baseline characteristics of the study population
| N | All women | Self-reported RA | Self-reported RA with available medical records | Confirmed RA after chart review | Identified RA with devised algorithms |
| (n=98 995) | (n=2692) | (n=305) | (n=129) | (n=964) | |
| Age at Q1 (years) | 49.4 (6.7) | 51.1 (6.7) | 49.6 (5.6) | 48.5 (5.2) | 50.2 (6.3) |
| Year of birth | |||||
| <1930 | 7808 (7.9) | 278 (10.3) | 13 (4.3) | 2 (1.6) | 59 (6.1) |
| (1930–1940) | 31 529 (31.9) | 1114 (41.4) | 112 (36.7) | 37 (28.7) | 380 (39.4) |
| (1940–1950) | 56 647 (57.2) | 1247 (46.3) | 177 (58.0) | 88 (68.1) | 509 (52.8) |
| ≥1950 | 3011 (3.0) | 53 (2.0) | 3 (1.0) | 2 (1.6) | 16 (1.7) |
| Body mass index at Q1 (kg/m²) | 22.6 (3.2) | 23.2 (3.4) | 23.0 (2.9) | 22.9 (2.9) | 23.0 (3.4) |
| Smoking status | |||||
| Not available | 945 (1.0) | 17 (0.6) | 0 (0) | 0 (0) | 7 (0.7) |
| Current smoker | 14 755 (14.8) | 420 (15.6) | 40 (13.1) | 16 (12.4) | 158 (16.4) |
| Non smoker | 53 130 (53.7) | 1465 (54.4) | 176 (57.7) | 75 (58.1) | 504 (52.3) |
| Former smoker | 30 165 (30.5) | 790 (29.4) | 89 (29.2) | 38 (29.5) | 295 (30.6) |
| Passive smoking in childhood | 12 854 (13.0) | 398 (14.8) | 48 (15.7) | 19 (14.7) | 158 (16.4) |
| Education level | |||||
| Not available | 4277 (4.3) | 136 (5.1) | 14 (4.6) | 5 (3.9) | 55 (5.7) |
| <High school | 16 185 (16.4) | 597 (22.2) | 61 (19.9) | 19 (14.7) | 186 (19.3) |
| Up to 2 years after high school | 44 986 (45.4) | 1186 (44.1) | 131 (43.0) | 57 (44.2) | 432 (44.8) |
| ≥3 years after high school | 33 547 (33.9) | 773 (28.6) | 99 (32.5) | 48 (37.2) | 291 (30.2) |
| Socio-professional category | |||||
| Not available | 15 800 (16.0) | 337 (12.5) | 25 (8.2) | 11 (8.5) | 106 (11.0) |
| Teacher | 62 013 (62.6) | 1632 (60.6) | 198 (64.9) | 86 (66.7) | 609 (63.2) |
| Higher managerial and professional occupations | 2499 (2.5) | 83 (3.1) | 9 (3.0) | 3 (2.3) | 28 (2.8) |
| Intermediate occupations | 15 340 (15.5) | 495 (18.4) | 58 (19.0) | 27 (20.9) | 179 (18.6) |
| Unemployed | 2602 (2.6) | 106 (3.9) | 10 (3.3) | 1 (0.8) | 28 (2.8) |
| Other | 741 (0.8) | 39 (1.5) | 5 (1.6) | 1 (0.8) | 14 (1.5) |
| Deprivation index | −0.3 (1.0) | −0.2 (1.0) | −0.1 (1.0) | −0.2 (0.9) | −0.3 (1.1) |
Results are presented as n (%) for categorical variables and mean (SD) for continuous variables.
RA, rheumatoid arthritis.