Association of Vitamin E Intake with All-Cause Mortality Among Individuals with Rheumatoid Arthritis: A Cohort Study from the NHANES 1999-2018

Abstract

Background The relationship between dietary vitamin E intake and mortality rates among rheumatoid arthritis (RA) patients remains a relatively uncharted territory in nutritional epidemiology, underscoring an important gap in research. Objectives This study is to explore the potential association between dietary vitamin E intake and all-cause mortality in the RA patient population. Methods This longitudinal cohort study analyzed 2,906 RA patients aged 20 years or older who participated in the National Health and Nutrition Examination Survey from 1999 to 2018. Comprehensive data on mortality, dietary vitamin E intake, and pertinent confounding variables were systematically collected and analyzed using Cox regression and spline curve fitting to analyze the potential association. Results Following the adjustment for confounding factors, a significant inverse relationship was identified between dietary vitamin E intake and the risk of all-cause mortality in patients with RA. The adjusted hazard ratios (HRs) for the second (Q2), third (Q3), and fourth (Q4) quartiles of vitamin E intake were 0.85, 0.60, and 0.68, respectively. Non-linear modeling indicated a threshold effect characterized by a curve that associated dietary vitamin E intake with mortality risk (p = 0.016). An intake threshold of 7.097 mg/day was identified, below which each unit increment in vitamin E intake was associated with a 11.1% decrease in all-cause mortality risk (HR = 0.889). Conversely, for intakes surpassing this threshold, no significant relationship with mortality risk was detected (HR = 1.0038). Conclusion The findings of this study indicate a beneficial relationship between elevated dietary vitamin E intake and a reduced risk of all-cause mortality in RA patients. The dose-response relationship exhibits a non-linear pattern, featuring a critical inflection point at an intake of approximately 7.097 mg/day.