Characteristics of study population of Swedish women with RA 2006–2016, and matched population referents
| RA | Population referents | |
| Persons (N) | 15 921 | 79 441 |
| Birth year (Q1–Q4) | 1952 (1940–1963) | 1952 (1940–1963) |
| Mean age at entry (SD) | 59 (16) | 59 (16) |
| Education (%) | ||
| 9 years or less | 27 | 25 |
| 10–12 years | 56 | 55 |
| More than 12 years | 15 | 19 |
| RA in a first-degree relative (%) | 10 | 4 |
| Breast or ovarian cancer in a first-degree relative (%) | 10 | 10 |
| Invasive cancer prior to entry (%) | 5 | 6 |
| Country of birth (%) | ||
| Sweden | 84 | 83 |
| Rest of Europe | 11 | 11 |
| Rest of the world | 5 | 6 |
| ACPA and RF negative | 28 | NA |
| ACPA or RF positive | 68 | NA |
| Mean age at first live birth (SD) | 25 (5.0) | 25 (5.0) |
| Children at index date (SD) | 2 (1.4) | 2 (1.4) |
| Combined oestrogen and progestin HRT (%) | 5 | 5 |
| Unopposed oestrogen HRT (%) | 6 | 6 |
| Combined oestrogen and progestin contraceptive (%) | 9 | 9 |
| Progestin only contraceptive (%) | 7 | 7 |
ACPA, Anti-citrullinated protein antibodies; HRT, hormone replacement therapy; RA, rheumatoid arthritis; RF, Rheumatoid factor.