The effect of oral contraceptives and estrogen replacement therapy on the risk of RA

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J Rheumatol. 2004 Feb;31(2):207-13.

The effect of oral contraceptives and estrogen replacement therapy on

the risk of rheumatoid arthritis: a population based study.

Doran MF, Crowson CS, O'Fallon WM, SE.

Department of Rheumatology, Mater Misericordiae University Hospital,

Dublin, Ireland.

OBJECTIVE: Epidemiologic evidence for a protective effect of exogenous

female sex hormones on the development of rheumatoid arthritis (RA) is

contradictory. We examined whether exposure to either oral

contraceptives (OC) or postmenopausal estrogen replacement therapy (ERT)

is associated with the development of RA in women. METHODS: We

separately examined the relationship between use of OC and ERT on the

risk of RA in a population based case-control study. Case patients,

including all female residents of Rochester, Minnesota, >/= 18 years of

age, who first fulfilled 1987 American College of Rheumatology criteria

for RA between 1955 and 1994 (n = 445), were compared with age matched

female controls from the community. Multivariable conditional logistic

regression models were used to determine whether OC or ERT exposure had

an effect on RA development after controlling for potential confounders.

RESULTS: We observed an inverse association between ever-use of OC and

the risk of RA, which persisted after adjusting for potential

confounders in multivariate analyses (OR 0.56, 95% CI 0.34, 0.92).

Earlier calendar-year of first exposure to OC was associated with lower

OR for RA. We found no evidence of a significant association of ERT with

RA risk (adjusted OR 1.11, 95% CI 0.69, 1.78).

CONCLUSION: Exposure to OC, but not ERT, significantly reduces the risk

of development of RA. The risk of developing RA is lower when OC

exposure occurred in earlier years, which suggests that the higher doses

of estrogens and progestins contained in earlier OC preparations may

have a stronger protective effect against developing RA. While this

protective effect is strong, it only explains a small portion of the

observed decrease in RA incidence over the past few decades because the

proportion of Rochester women exposed to OC is quite small.

PMID: 14760786

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