Study Finds Oral Contraceptives Decrease Risk of Rheumatoid Arthritis

The use of oral contraceptives (OC) decreases the risk of rheumatoid arthritis (RA), according to a new study. However, the researchers did not find a link between breastfeeding and a reduced risk of ACPA-positive or ACPA-negative RA.

A study published in Annals of Rheumatic Diseases investigated whether OC use or breastfeeding affected the risk of developing RA using data collected from the Swedish Epidemiological Investigation of RA (EIRA), which consisted of women older than 18 years who lived in Sweden between 1996 and 2014. Each participant completed a lifestyle questionnaire that considered OC use and breastfeeding, in addition to potential confounders. A total of 2676 cases and 4251 controls were identified and completed the questionnaire, between 1996 and 2014.

“RA is among the most common autoimmune diseases, with a complex interplay of genetic and environmental factors involved in its aetiology,” the authors wrote. “Since the disease is 2 to 3 times more common among women as compared with men, it has been suggested that hormonal and reproductive factors might partly explain this sex difference.”

The study considered the residential area, smoking, and alcohol consumption of the participants to identify their interaction with RA. The results found that compared to those who have never used OCs, those with past or current OC use had a decreased risk of ACPA-positive RA, while the research did not suggest any associations with ACPA-negative RA. However, long duration OC use decreased the risk of both positive and negative ACPA RA.

Furthermore, a history of breastfeeding was linked to a decreased risk of only ACPA-positive RA in a dose-dependent manner, but did not remain following adjustments, according to the study. There was also a significant interaction between the lack of OC use and smoking for the risk of ACPA-positive RA.

“In summary, we found an inverse relationship between OC use and the subsequent development of RA, especially ACPA-positive RA,” the researchers noted. “An interaction between never OC use and smoking was also observed for this subgroup of disease, implying that among smokers, the risk was more pronounced in never OC users than in ever OC users.”

The researchers suggested the need for additional studies to confirm the influence of hormonal factors on the ACPA subsets of RA.