Objective: To examine the relation between postmenopausal hormone use and development of systemic lupus erythematosus.
Design: Prospective cohort study.
Setting: Nurses' Health Study.
Patients: 69,435 women aged 30 to 55 years in 1976 who reported that they had completed menopause and did not have systemic lupus erythematosus or any connective tissue disease were followed every 2 years from 1976 to 1990. These women were classified as never- or ever-(current and past) users of postmenopausal hormones.
Measurements: Incidence rates of systemic lupus erythematosus and classification criteria from the American College of Rheumatology that were confirmed by chart review.
Results: With never-users of postmenopausal hormones as the reference group, age-adjusted relative risks for systemic lupus erythematosus (n = 45 women) were 2.1 (95% CI, 1.1 to 4.0) for ever-users, 2.5 (CI, 1.2 to 5.0) for current users, and 1.8 (CI, 0.8 to 4.1) for past users. A proportional increase in the risk for systemic lupus erythematosus was observed that was related to the duration of use of postmenopausal hormones (test for trend, P = 0.011).
Conclusions: Postmenopausal hormone therapy is associated with an increased risk for developing systemic lupus erythematosus.