Coffee consumption may suppress development of metabolic syndrome in patients with rheumatoid arthritis -TOMORROW study.

Objectives This study aimed to clarify the associations between metabolic syndrome (MetS) and rheumatoid arthritis (RA), and between MetS and dietary factors in RA patients. Methods Data were analyzed from a prospective cohort study that began in 2010, comprising 208 RA patients and 205 gender- and age-matched controls. The MetS components (blood pressure, lipid metabolism, glucose metabolism, and waist circumference) were evaluated up to 2017. Dietary intake was assessed in 2011. The effect of covariates for development of MetS among participants without MetS in 2010 was tested using Cox proportional hazard modeling. Results In an analysis of overall subjects, RA was not significantly associated with development of MetS [Hazard ratio (HR): 0.86, 95% confidential intervals (CI): 0.51, 1.46]. In RA patients, regularly consuming coffee (<1 cup/day: HR 0.24, 95%CI 0.09, 0.64; ≥1 cup/day: HR 0.25, 95%CI 0.10, 0.62) was significantly associated with a suppressive effect on development of MetS, compared with non-coffee drinkers. In a complementary analysis, total coffee consumption (filter, instant, decaffeinated) ≥1 cup/day, was significantly associated with development of MetS (HR 0.33, 95%CI 0.13,0.82). Conclusions RA was not significantly associated with development of MetS and coffee intake may be associated with absence of MetS in RA patients.