Effects of adherence to mediterranean diet on rheumatoid arthritis impact of disease (RAID) score

Background: Mediterranean diet (MD) is a well-balanced, nutritionally adequate and potentially anti-inflammatory diet that encompasses all food groups. Presently, there are conflicting data about the benefits of MD in rheumatoid arthritis (RA). Not enough evidence support a role of MD in the prevention and treatment of RA, and a modest impact of MD on laboratory parameters has been described. Greater effect on subjective aspects of the disease such as joint pain, morning stiffness, and fatigue was reported. Objectives: To investigate whether the adherence to MD affects RA perception as measured by Rheumatoid Arthritis Impact of Disease (RAID) score. Methods: Consecutive patients <65 years with RA attending our outpatient clinic were enrolled in this cross-sectional study. For each patient we collected: 1) RAID that consists of 7 single-item domains (pain, functional disability, fatigue, sleep, physical well-being, emotional well-being and coping), each rated by patients on an 11-point numerical rating scale from 0 (best) to 10 (worst) [1], and 2) MD score, a self-reported questionnaire that evaluates the adherence to MD through the consumption of 11 food groups, ranging from 0 (no adherence) to 55 (high adherence) [2]. Univariate analysis was performed using MD score as independent variable. Moreover, to evaluate the adjusted relationship between the single item of RAID and MD score, a multiple regression model was used. Results: 205 RA patients were enrolled: median age at visit 53 (q1-q3: 44-59) years, female 80.5 %. The median MD and RAID score were 35 (q1-q3: 32-39) and 2.42 (q1-q3: 0.63-4.51) respectively. RAID total score had a statistically significant negative relationship with MD score (regression coefficient -0.08; p-value=0.016). Concerning the single RAID items, a statistically significant negative association was found for pain (regression coefficient -0.08; p-value=0.025), functional disability (regression coefficient -0.13; p-value<0.001), sleep (regression coefficient -0.08; p-value=0.041), physical well-being (regression coefficient -0.08; p-value=0.027) and coping (regression coefficient -0.11; p-value=0.008). Multiple regression analysis to evaluate the relationship between significant RAID items and MD score did not show any statistical significance as all items are strongly related to each other. Conclusion: To our knowledge, this is the first study addressing the relationship between the adherence to MD and the perception of RA impact. A better MD adherence was associated with lower self-reported composite total RAID score as well as lower pain, functional disability, sleep, physical well-being and coping. The effect of MD adherence on overall RAID is relevant but, at the same time, a prominent effect of one single item on the others could not be documented. This study confirmed the importance of non-pharmacological interventions, such as diet, in RA management.