To clarify the relationship between dietary habit and disease activity of rheumatoid arthritis (RA).
This study enrolled RA patients who met the ACR/EULAR 2010 classification criteria from Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) cohort in 2015. 22-item food frequency questionnaire (FFQ) was taken for the measurement of dietary habit in a single-institution cohort of RA (Kyoto University Rheumatoid Arthritis Management Alliance: KURAMA) in 2015. The disease activities of RA using the Disease Activity Score calculated based on the erythrocyte sedimentation rate (DAS28-ESR), Simplified Disease Activity Index (SDAI), Health Assessment Questionnaire (HAQ), and serum matrix metalloproteinase-3 (MMP-3) level, the use of disease-modifying anti-rheumatic drugs (DMARDs), disease duration, rheumatoid factor, anti-cyclic citrullinated antibody, and body mass index were also examined. All of them were combined and statistically analyzed.
441 RA patients (81% women; mean age 65 years; mean disease duration 15 years) were enrolled from the KURAMA cohort. Average Disease Activity Score-28 using the erythrocyte sedimentation rate (DAS28-ESR) was 2.7. Univariate analysis showed that intake frequency of vegetables had a statistically significant negative correlation with disease activity markers, such as DAS28-ESR (ρ = -0.11, p<0.01), Simplified Disease Activity Index (SDAI) (ρ = -0.16, p<0.001), matrix metalloproteinase-3 (MMP-3) (ρ = -0.21, p<0.0001), and Health Assessment Questionnaire (HAQ) (ρ = -0.13, p<0.01). Factor analysis with varimax rotation was done to simplify the relevance of disease activity to various food items. 22 foods were categorized into five dietary patterns: "seafoods", "vegetables/fruits", "meats/fried foods", "snacks", and "processed foods". The multivariate analysis adjusted for clinically significant confounders showed that "seafoods" had statistically significant negative correlations with DAS28-ESR (β = -0.15, p<0.01), SDAI (β = -0.18, p<0.001), MMP-3 (β = -0.15, p<0.01), and HAQ (β = -0.24, p<0.0001). "Vegetables/fruits" had statistically significant negative correlations with SDAI (β = -0.11 p<0.05), MMP-3 (β = -0.12, p<0.01), and HAQ (β = -0.11, p<0.05).
These results suggest that high intake frequency of vegetables/fruits and/or seafoods might correlate with low disease activity.