Past use of oral contraceptives and the risk of developing systemic lupus erythematosus

Objective. To examine the relationship between past use of oral contraceptives (OCs) and development of systemic lupus erythematosus (SLE). Methods. Prospective cohort study of 121,645 women who were followed up every 2 years between 1976 and 1990 as part of the Nurses' Health Study, Women were classified as never users or past users of OCs based on self-report, Incidence of SLE was defined by 1) strict American College of Rheumatology (ACR) classification criteria (greater than or equal to 4 ACR criteria), 2) greater than or equal to 4 ACR criteria and any physician's diagnosis, 3) greater than or equal to 4 ACR criteria and diagnosis by an ACR-certified rheumatologist, 4) greater than or equal to 3 ACR criteria, or 5) diagnosis by a physician even if the patient did not meet the ACR criteria. Results. Compared with never users of OCs, and after adjusting for age and ever use of postmenopausal hormones, the relative risk (95% confidence interval [95% CI]) for the incidence of SLE in the women who had definite cases of SLE (greater than or equal to 4 ACR criteria) (n=99) was 1.4 (0.9-2.1) for past users of OCs. Using the most stringent case definition (ACR criteria plus a diagnosis of SLE by an ACR member) (n=58), the relative risk for past users compared with never users was 1.9 (95% CI 1.1-3.3). No relationship was observed between duration of OC use or time since first use and the risk of developing SLE.