Table 2

Relative risk of breast cancer in RA versus general population comparators (cohort study), adjusted for, age, country of birth, educational level, HRT, oral contraceptives, age at first birth, number of children, family history of breast cancer/ovarian cancer, previous invasive cancer and calendar year

Patients with RA, NumberPopulation comparators, NumberHR (95% CI)
Overall19011910.80 (0.68 to 0.93)
Exposure variants
 RA, 18–49 years181550.59 (0.36 to 0.97)
 RA, 50–75 years1468410.87 (0.73 to 1.03)
 RA, >75 years261950.68 (0.45 to 1.03)
 RA 18–50 and breast cancer <50 years9530.86 (0.42 to 1.75)
 Seronegative RA553460.77 (0.58 to 1.02)
 Seropositive RA1247720.81 (0.67 to 0.98)
Outcome variants
 Breast cancer, 18–50 years91020.47 (0.24 to 0.93)
 Breast cancer, >50 years18110890.83 (0.71 to 0.97)
 Stage 012970.63 (0.34 to 1.14)
 Stage 1854900.87 (0.69 to 1.09)
 Stage 2603750.80 (0.61 to 1.05)
 Stage 34410.49 (0.17 to 1.36)
 Stage 46300.99 (0.41 to 2.39)
  • HRT, hormone replacement therapy; RA, rheumatoid arthritis.