Interaction between rheumatoid arthritis and mediterranean diet on the risk of cardiovascular disease for the middle aged and elderly from National Health and Nutrition Examination Survey (NHANES)

BACKGROUND: Cardiovascular diseases (CVD) occurrence were associated with rheumatoid arthritis (RA) and Mediterranean diet (MD), but few studies have been conducted to explore the combined effect. This study was to outline the relationship of coexistence of RA and MD on the risk of CVD based on the National Health and Nutrition Examination Survey (NHANES) database. METHODS: The data of this cross-sectional study was from the NHANES 2005–2010. The definition of CVD and RA was based on the self-reported questions, respectively; and the alternate MD Index assessed all participants’ adherence to the MD. Weighted multivariate logistic regression was adopted to explore the relationship of RA, MD on the risk of CVD, and coexistence effect of RA and MD. The additive interaction was evaluated by the relative excess risk due to interaction (RERI), attributable proportion (AP) and the synergy index (SI). The multiplicative interaction was evaluated by odds ratio (OR) and 95% confidence interval (CI) of product-term. RESULTS: A total of 3,352 participants from NHANES database who were divided into CVD group (n = 385) and non-CVD group (n = 2,967). The result indicated that RA (Model 1: OR = 3.98, 95%CI: 2.76–5.73; Model 2: OR = 2.65, 95%CI: 1.69–4.16) and low adherence to the MD (Model 1: OR = 1.82, 95%CI: 1.13–2.93; Model 2: OR = 1.67, 95%CI:1.01–2.77) was associated with an increased risk of CVD, respectively. Additionally, we observed the additive (RERI = 4.76, 95% CI: 0.52-9.00; AP = 0.74, 95% CI: 0.54–0.95; SI = 8.21, 95% CI: 1.48–45.51) and multiplicative (OR = 3.63, 95% CI: 1.44–9.15) interaction of RA and low adherence to the MD on the risk of CVD. CONCLUSION: RA and MD were associated with CVD occurrence, respectively, and there may be an interaction between RA and MD for the development of CVD. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-023-15478-1.