RA Risk Lowered By Long-Term Oral Contraceptive Use

A recent study showed that long-term use of oral contraceptives is associated with a lower risk of anticitrullinated protein antibody-positive (ACPA-positive) and ACPA-negative rheumatoid arthritis (RA), with a particularly low risk of ACPA-positive RA among users who smoke. However, breastfeeding was not associated with a lower risk of either type of RA.

In the Swedish Epidemiological Investigation of RA study, the researchers evaluated 2641 women aged 18 years or older with RA and 4251 controls. An extensive questionnaire regarding oral contraceptive use, breastfeeding, and potential confounders was administered to all participants.
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Overall responses were calculated with 95% confidence intervals. Results were adjusted for age, residential area, smoking, and alcohol consumption. Additionally, the researchers assessed the presence of interaction.

Results indicated that women who had ever used oral contraceptives and those who had used them in the past had a lower risk of ACPA-positive RA, compared with participants who had never used oral contraceptives. The researchers observed no significant associations for ACPA-negative RA. However, participants who had used oral contraceptives for more than 7 years had a decreased risk of both ACPA-positive and ACPA-negative RA, compared to never users.

The researchers found that a history of long-term breastfeeding decreased the risk of only ACPA-positive RA in a dose-dependent manner. However, this trend disappeared after the results were adjusted. A significant interaction was found between the lack of oral contraceptive use and smoking on the risk of ACPA-positive RA, whereas no interactions were found for breastfeeding.

“[Oral contraceptives] decreased the risk of RA, especially ACPA-positive RA, where an interaction with smoking was observed,” the researchers concluded. “A long duration of [oral contraceptive] use decreased the risk of both disease subsets. We could not confirm an association between [breastfeeding] and a decreased risk of either ACPA-positive or ACPA-negative RA.”

—Christina Vogt

Reference:

Orellana C, Saevarsdottir S, Klareskog L, Karlson EW, Alfredsson L, Bengtsson C. Oral contraceptives, breastfeeding and the risk of developing rheumatoid arthritis: results from the Swedish EIRA study [Published online August 17, 2017]. Ann Rheum Dis. doi:10.1136/annrheumdis-2017-211620.