Inflammatory dietary pattern and risk of developing rheumatoid arthritis in women

Our objective was to investigate whether a dietary pattern derived using inflammatory biomarkers is associated with rheumatoid arthritis (RA) risk. We prospectively followed 79,988 women in the Nurses’ Health Study (NHS, 1984–2014) and 93,572 women in the NHSII (1991–2013); incident RA was confirmed by medical records. Food frequency questionnaires (FFQ) were completed at baseline and approximately every 4 years. Inflammatory dietary pattern was assessed from FFQ data using the Empirical Dietary Inflammatory Pattern (EDIP), including 18 anti-/pro-inflammatory food/beverage groups weighted by correlations with plasma inflammatory biomarkers (interleukin-6, C-reactive protein, and tumor necrosis factor-α receptor 2). We investigated associations between EDIP and RA using Cox regression. We identified 1185 incident RA cases over 4,425,434 person-years. EDIP was not associated with overall RA risk (p trend = 0.21 across EDIP quartiles). Among women ≤ 55 years, increasing EDIP was associated with increased overall RA risk; HRs (95% CIs) across EDIP quartiles were 1.00 (reference), 1.14 (0.86–1.51), 1.35 (1.03–1.77), and 1.38 (1.05–1.83; p for trend = 0.01). Adjusting for BMI attenuated this association. Increasing EDIP was associated with increased seropositive RA risk among women ≤ 55 years (p for trend = 0.04). There was no association between EDIP and RA among women > 55 years (EDIP-age interaction, p = 0.03). An inflammatory dietary pattern was associated with increased seropositive RA risk with onset ≤ 55 years old, and this association may be partially mediated through BMI.