Objectives To evaluate the association between long-term dietary quality, measured by the 2010 Alternative Healthy Eating Index, and risk of rheumatoid arthritis (RA) in women.
Methods We prospectively followed 76 597 women in the Nurses' Health Study aged 30–55 years and 93 392 women in the Nurses' Health Study II aged 25–42 years at baseline and free from RA or other connective tissue diseases. The lifestyle, environmental exposure and anthropometric information were collected at baseline and updated biennially. Cumulative follow-up rates were more than 90% for both cohorts. The primary outcome was RA alone with two subtypes of the disease: seropositive and seronegative RA.
Results During 3 678 104 person-years, 1007 RA cases were confirmed. In the multivariable-adjusted model, long-term adherence to healthy eating patterns was marginally associated with reduced RA risk. To assess potential effect modification by age at diagnosis, we stratified by age. Among women aged ≤55 years, better quality diet was associated with lower RA risk (HRQ4 vs Q1: 0.67; 95% CI 0.51 to 0.88; p trend: 0.002), but no significant association was found for women aged >55 years (p interaction: 0.005). When stratifying by serostatus, the inverse association among those aged ≤55 years was strongest for seropositive RA (HRQ4 vs Q1: 0.60; 95% CI 0.42 to 0.86; p trend: 0.003).
Conclusions A healthier diet was associated with a reduced risk of RA occurring at 55 years of age or younger, particularly seropositive RA.
- Rheumatoid Arthritis
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Handling editor Tore K Kvien
Contributors YH and BL designed the study, analyse the data and wrote the first draft. SM contributed to the data analysis. BL, EWK, KHC, JAS and FBH were involved in data collection. All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. YH and BL had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding This study was supported by the National Institutes of Health under Award Number AR061362, AR049880, AR052403, AR047782, AR059073, AR066953, AR069688, AR066109 and CA186107, CA176726, CA49449, CA67262. Dr Sparks was also supported by the Rheumatology Research Foundation Scientific Development Award. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Competing interests None declared.
Ethics approval Partners Health Care, Inc.
Provenance and peer review Not commissioned; externally peer reviewed.